Dynamics 365 Base vs Attach Licensing Explained: Cut Costs and Optimize Multi-App Users
Dynamics 365 Base vs Attach Licensing Explained
Dynamics 365 offers a flexible licensing model that can significantly cut costs for multi-app users. At the heart of this model is the concept of Base vs. Attach licenses.
In simple terms, each user requires one base license (their primary app at full price), and any additional apps for that same user can be added as attached licenses at a significantly lower cost.
This approach is Microsoft’s way of ensuring companies don’t pay double when one person needs access to multiple Dynamics 365 applications. Read our ultimate guide to Microsoft Dynamics licensing and negotiations.
This model is a top cost optimization lever for enterprises, yet it’s often misunderstood. Many organizations still overpay by assigning separate full licenses for each app a user needs, not realizing that those secondary licenses could be discounted attachments.
In this article, we’ll break down how base vs. attach licensing works and demonstrate how to use it strategically – from optimizing internal license assignments to strengthening your position in negotiations with Microsoft.
Why Base vs Attach Licensing Matters
Licensing is usually the largest component of Dynamics 365’s total cost.
For CIOs, procurement leaders, and IT managers, every dollar counts. Base vs attach licensing matters because it directly targets one of the most common areas of overspend: users who require multiple Dynamics 365 apps.
Without the base+attach model, an employee requiring two or three Dynamics modules would need multiple full-price licenses, dramatically increasing costs.
Microsoft introduced the base and attach structure as a built-in cost optimization mechanism. It’s essentially an official discount program for multi-app users.
However, if this model is misunderstood or misapplied, enterprises can overspend by tens or hundreds of thousands of dollars.
For example, assigning two separate full licenses when one could be an attachment means paying double for that user’s access. In large organizations, such mistakes, when multiplied across departments, lead to significant waste.
Therefore, understanding and applying base vs attach licensing correctly is a quick win for cost savings and should be a priority in your Dynamics 365 license strategy.
How Dynamics 365 Base vs Attach Licensing Works
Under Microsoft’s licensing rules, every user’s first Dynamics 365 application must be a Base license. The base license is a standard, full-cost subscription for a core app (such as Sales, Customer Service, or Finance) assigned to a specific user.
This base license gives the user full rights to that application’s functionality. Crucially, each user requires only one base license, regardless of the number of different Dynamics 365 apps they use.
Once a user has a base license, attach licenses come into play for any additional apps. An attach license is a discounted add-on license for the same user.
It grants the user full access to a second (or third, and so on) Dynamics 365 application at a fraction of the price. Functionally, an attach license is identical to a base license for the same app – the user gets all the features of that app.
The only difference is cost: attach licenses are significantly cheaper than buying another full license. In fact, attached license pricing is often around 80% lower than the standalone price of the app.
There is an important rule for maximizing savings: the base license should be the highest-priced app the user actually needs. Microsoft’s model actually enforces that the first (base) license for a user be the most expensive one they use. This ensures that every other app can be attached at the lower rate.
For example, if a user requires Dynamics 365 Finance (an ERP module priced higher) and Dynamics 365 Sales (a CRM module at a lower price), you would assign Finance as the base license and Sales as an add-on.
The user pays full price for Finance and gets Sales for the discounted fee. If you tried it the other way around, Microsoft would not consider it a valid combination – the priciest app must be the base.
In cases where apps are similarly priced (e.g., Sales and Customer Service, both in the same range), you still only designate one as the base and buy the second as an attachment; it doesn’t matter which you pick as the base when prices are equal, as long as you don’t accidentally pay full price for both.
A single user can have an unlimited number of attached licenses as needed. There’s no hard cap on the number of additional apps one person can be attached to, provided each attachment is for a different Dynamics 365 application and the user maintains a qualifying base license.
This flexibility means an employee could theoretically use three or four Dynamics 365 modules (such as Sales, Customer Service, Field Service, and Marketing). In contrast, the company pays full price for just one of them and receives discounted pricing on all the others. It’s Microsoft’s way of bundling à la carte, replacing the old all-in-one bundles with a more customizable (and cost-effective) approach.
Why does Microsoft offer attach licenses at such a steep discount?
Two reasons: First, it encourages organizations to adopt multiple Dynamics 365 apps by lowering the incremental cost per additional app. Second, it prevents the perception of double-charging customers. Microsoft recognizes that a single user can only do so much in a month – charging them 100% price for two apps might feel punitive.
The attached model balances Microsoft’s revenue goals with a fairer cost to the customer. In the end, if used properly, it’s a win-win: the enterprise gets broader functionality at a lower marginal cost, and Microsoft gets a more deeply integrated customer (using more of the Dynamics ecosystem).
For more insights, read ” Dynamics 365 Renewal Negotiation Strategy: How to Secure Better Terms and Lower Costs.
Examples of Multi-App Users
To bring this to life, let’s consider a couple of common scenarios where base+attach licensing makes a big difference:
- Sales + Customer Service: Imagine an Account Manager who not only works on sales deals in Dynamics 365 Sales, but also handles post-sales support cases in Dynamics 365 Customer Service. Normally, you’d think this user needs two licenses – one for Sales and one for Customer Service – each costing around $95 per user/month (hypothetical example pricing). If you assigned two base licenses, you’d pay roughly $190/month for that user. Under the base vs attach model, you would buy one of these (say Sales) as the base license at full price ($95), and then get the Customer Service app as an attach license. The attachment might cost only about $20/month for that additional app. Now, the user has access to both Sales and Customer Service for a total of approximately $115/month, instead of $190. That’s nearly a 40% cost reduction for the same user just by using the correct licensing combination. Multiply that savings by dozens of dual-role users, and the financial impact is huge.
- Finance + Supply Chain (ERP combo): In many enterprises, an operations manager or finance analyst might need to use both Dynamics 365 Finance and Dynamics 365 Supply Chain Management (SCM) to do their job. These are high-end ERP modules, often priced higher than the CRM apps. Let’s say a Finance or SCM license runs around $180 per user/month on its own. If a user needs both, paying full price for each would be $360/month for that user – an expensive proposition. With base+attach, you’d assign the higher of the two as the base (they’re similarly priced, but choose one as base at $180) and the second one as an attach for, say, $30/month (since ERP attaches tend to be a bit more than CRM attaches, but still far cheaper than full price). The combined cost becomes about $210/month for that user to have both Finance and SCM, instead of $360. This is a $150 monthly savings per user, or roughly 41% less cost. In practice, most Dynamics 365 Finance & Operations users employ this method – they license one ERP app fully and attach the other. This brings the effective cost of “Finance + Supply Chain for one user” down to an acceptable level (roughly equivalent to what one and a quarter full licenses would cost, rather than two full licenses).
- Cross-App Example – Finance and Sales: Consider a scenario where a business manager needs visibility into both the ERP (Finance) and CRM (Sales) sides. If the user already has a Finance base license, you can attach Dynamics 365 Sales to that user at the discounted rate. Therefore, a Sales Enterprise license, which would normally cost $95, can be added for approximately $20 as an attachment. The user benefits from both financial and customer relationship capabilities, and the company pays only a modest add-on fee for the Sales access. Without attached licensing, many organizations would shy away from giving an operations person a second CRM tool due to cost; with attached licensing, it becomes a feasible multi-functional user setup at a low incremental cost.
These examples show that attached licenses transform the cost equation for multi-app users. Instead of costs scaling linearly with each additional application a person needs, the attach model makes the second (or third) app dramatically cheaper.
Over the course of a year, the savings per user with one attached license can be several hundred dollars (and thousands for users with multiple attachments).
When scaled across an enterprise, the aggregate savings can reach into the hundreds of thousands or even millions in large deployments.
Just as importantly, this model enables users to have all the Dynamics 365 tools they need without teams feeling like they must restrict access to save money. It aligns licensing costs more closely with actual usage per user.
Common Mistakes in Applying Base vs Attach
Despite the clear benefits, companies often stumble when executing a base-plus-attach strategy.
Here are some common mistakes to watch out for:
1. Assigning multiple base licenses to one user: This is the classic error – paying full price twice (or more) for the same person. It usually happens when licensing decisions are made in silos. For example, the sales department purchases a Sales license for Alice, while the customer service department separately purchases a Customer Service license for her. Alice ends up with two base licenses in the system, and the company is unknowingly overpaying for them. How to avoid it: Always check if a user already has a Dynamics 365 license before purchasing another. If they do, and they need another app, plan to make it an attached license. No user should have two standalone full licenses. If you discover any existing users in that situation, remediate it by converting one of those licenses to an attach (Microsoft allows this adjustment via your license provider or at true-up).
2. Lack of centralized license governance: The above mistake is often a symptom of decentralized licensing. When each department or project team handles its own Dynamics 365 licensing, it may not be aware of the other licenses held by the same employee. This can lead to duplicate base licenses and missed attach opportunities. The governance solution is to centralize or at least coordinate license assignment. A centralized licensing or IT asset management team can oversee requests for new licenses and identify when a user should receive an attachment instead of a new base. By implementing clear internal policies (e.g., “IT must approve any Dynamics license assignment”), you can prevent well-meaning managers from unknowingly overspending.
3. Choosing the wrong app as the base license: While Microsoft’s rules require the first license to be the highest priced, sometimes license purchasers don’t realize this, or the price difference isn’t obvious. If a user needs two apps of different prices and you mistakenly make the cheaper app the base, you could encounter two problems: you might violate the licensing rules, and you’ll also lose savings (because the more expensive app might not be eligible as an attachment to a cheaper base). For instance, making a $95 app the base when the same user also needs a $180 app means you can’t attach the $180 one – that user would incorrectly end up with two full licenses or an ineligible combination. The order matters: always assign the most expensive required app as the base license, then attach the others. In the case of equally priced apps (like two CRM modules), you still only buy one as a base and one attachment – which one is the base won’t affect the cost, but you must remember to attach the second rather than buying both full. A related mistake is improperly mixing editions: e.g., using a lower-tier “Professional” edition license as a base when the user also needs an “Enterprise” edition app – typically, attachments are only allowed among Enterprise-tier apps. Misjudging this can lead to compliance issues or not being able to attach at all. The best practice is to standardize on Enterprise licenses for any user who may need multiple apps, ensuring that all their required modules can attach seamlessly.
Aside from these, another common oversight is failing to train or inform the relevant stakeholders about the base vs. attach concept. If procurement officers, IT staff, and department heads aren’t aware of it, they might unintentionally opt for the familiar route of separate licenses per app.
Spreading awareness of how base+attach works is key to avoiding all these mistakes. One way is to incorporate a check in the license request process: “Does this user already have a Dynamics 365 license?” If yes, evaluate if the new app can be attached.
Cost Optimization Through Base vs Attach Strategy
Enterprises can unlock substantial Dynamics 365 licensing optimization by systematically using base vs attach licensing.
Here’s how to turn this model into a core cost-saving strategy:
- Enforce a “One Base per User” Policy: Make it an internal rule that no user gets a second full Dynamics 365 license without justification. If User X needs another module, the default action should be to provide them with an attached license. By codifying this policy, you set the expectation across IT and procurement that base+attach is the norm. Many organizations even configure their license management tools to flag or prevent assigning a second base license to the same user account.
- Centralized License Management: As mentioned, central governance is critical. Have a single team or licensing manager oversee all Dynamics 365 licensing requests. This team should maintain a license inventory or matrix that shows each user and which licenses (base or attach) they have. With this visibility, it’s easier to spot if someone requests a license that would violate the one-base rule. Central oversight also helps ensure consistency – for example, ensuring that everyone uses the correct base for each attachment combination and that any new Dynamics app rollout utilizes attachments for existing users.
- Regular Audits and True-Ups: Conduct periodic audits of user licensing. Specifically, look for redundant licenses (any user with more than one full license) and misalignments (cases where someone might have an attachment without a proper base, or two bases where one should be attached). Microsoft’s true-up process (annual adjustments in enterprise agreements) is an opportunity to fix these. Before true-up or renewal, identify where you can convert licenses to attach. Turn down any unnecessary full licenses and reassign them as attached licenses. Not only does this save money immediately, but it also resets your baseline at a lower level for the next contract period.
- Monitor Roles vs. Licenses: Dynamics 365 usage can evolve – an employee might take on new responsibilities requiring another app, or conversely, they might no longer need a second app they once had. Establish a process to regularly review whether license assignments still align with job roles. If a user with only one license is now doing dual roles, don’t wait – give them an attach license for the second app instead of a workaround or, worse, sharing accounts (which is non-compliant). If someone no longer needs a module, remove the attached license to save cost. Optimization is ongoing: treat licenses as dynamic, not set-and-forget.
- Educate Departments: Ensure that department heads and application owners understand the base+attach model. When planning new projects or expanding Dynamics usage, they should budget for one base per user and attach for any additional apps those users will need. By incorporating this into governance guidelines or training, you can reduce pushback and confusion. It simply becomes the way your company licenses Dynamics 365: one primary license per user, everything else rides at a discount.
By executing these strategies, enterprises have seen significant cost savings. Some organizations have reported reducing their Dynamics 365 licensing expenses by 20-30% or more through diligent base vs attach usage, especially if they had many multi-app users to begin with.
Moreover, beyond the raw savings, this approach enhances compliance (since you’re following Microsoft’s intended model) and can simplify license management (with fewer full licenses to track and a clearer understanding of who has what).
Using Base vs Attach in Negotiations with Microsoft
The base+attach strategy isn’t just an internal cost tool – it can also strengthen your position when negotiating with Microsoft for license renewals or enterprise agreements. Here’s how:
Lowering the “Perceived Demand”: When you embrace attach licensing, the number of full-price licenses (bases) you truly need is lower than it would be if you licensed every app separately. Microsoft sales reps often forecast your needs in terms of full licenses, but you can come to the table with a lower count of base licenses by demonstrating your attach approach. For example, instead of saying “We need 200 Sales and 200 Customer Service licenses” (which a naive calculation would double-count 200 users needing both), you can say “We need 200 base licenses and 200 attach licenses.” This signals to Microsoft that you are an informed customer, minimizing unnecessary spend. It can temper their expectations regarding revenue and possibly make them more flexible with discounts, as they know you won’t be paying for 400 full licenses – only 200 full and 200 discounted attachments.
Bundle Your Base and Attach Plan in the Renewal: When negotiating your contract or renewal, explicitly include the base versus attach structure in your discussions. Break down your user counts by those who will have multiple apps. For instance, “We have 150 users who will each need two apps – we plan to license 150 bases and 150 attaches for them, plus an additional 300 single-app users with base licenses only.” By doing this, you set the stage for attaching pricing to all those extra app needs. This makes it harder for Microsoft to ignore or later upsell those attached users as if they were full license users. Essentially, you’re anchoring the deal around the expectation that the attach discount applies.
Leverage Attach Savings as Negotiation Capital: You can frame the cost difference achieved by attachments as money that can be invested elsewhere – possibly even within Microsoft’s ecosystem. For example, you might tell your Microsoft account manager, “By utilizing attach licenses, we’re saving approximately $X over the term. This is enabling us to consider adopting an additional Dynamics module (or Power Platform capability, etc.) that we wouldn’t have budget for otherwise.” This approach shows Microsoft that their own licensing construct (attached) is helping you expand in a controlled way. It positions the attach model as a positive-sum scenario rather than just you cutting their revenue. In some cases, Microsoft may respond with better pricing tiers or concessions on specific products, acknowledging that you are fully optimizing your purchases.
Negotiation Tip – Highlight Compliance and Value: Microsoft’s sales teams are aware of the base+attach model, but they may not always bring it up proactively. If you show that you are using it enterprise-wide, it also signals that you won’t tolerate overselling or double licensing. You might say, “We audited our licenses and ensured no user has two base licenses; we’re fully compliant and optimized. We expect our renewal quote to reflect this optimized state.” This puts gentle pressure on Microsoft not to quote or bundle unnecessary extras. Instead, they might focus on offering value in other ways (like bundling an add-on or providing a slight discount on the base license volume) to secure your renewal. Essentially, you are negotiating from a position of efficiency and knowledge, which can lead to greater respect and a more favorable outcome in the deal.
Finally, don’t forget that the attached model can reduce your committed spend, which might affect discount levels in enterprise agreements. Be prepared: if you drop a lot of full licenses by switching to attaches, Microsoft could push back on discount percentages (since your total revenue to them is lower). Counter this by emphasizing total value and long-term partnership – you’re using Microsoft’s own licensing design as intended, and you’re more likely to invest in other Microsoft technologies when you’re getting a good ROI on Dynamics. In negotiations, every bit of saved cost can be repurposed; for instance, you might negotiate to use some of the savings for additional support benefits or training credits, which Microsoft can position as value-added benefits. This way, you keep the savings in one area while possibly giving Microsoft a win in another, leading to a balanced agreement.
Strategic Recommendations for Enterprises
To wrap up, here are some key strategic recommendations for enterprises looking to maximize savings and efficiency with Dynamics 365 base vs attach licensing:
- Run a License Audit Before Renewals: Conduct a thorough audit of all Dynamics 365 user licenses several months before your contract renewal or true-up. Identify any base license duplication (users with more than one full license) or users who could be using attached licenses but aren’t. Clean this up before entering negotiations or renewing — it’s easier to secure savings upfront than to get refunds later. This audit will also reveal how much you stand to save, which builds a strong business case internally for optimizing licenses.
- Make Base+Attach a Core Governance Principle: Treat the base vs attach model as a core pillar of your Dynamics 365 governance and cost management. Incorporate it into your IT governance documentation and training. For example, have a section in your licensing policy that explicitly states the base+attach approach must be used for any multi-app user. When everyone from procurement to IT support knows this is a standard practice, it becomes second nature to apply it.
- Use Attach License Data in Microsoft Negotiations: As suggested, bring data to Microsoft showing how many attach licenses you’re utilizing or plan to utilize. This quantifies your cost-saving efforts. You can also ask Microsoft for forecast pricing on attachments if you plan to increase usage of certain apps. Sometimes, Microsoft might offer promotional deals (like a temporary further discount) if they know you’re looking to add more attachments (because that often means adopting a new app). Use the fact that you have, say, “50 Sales attaches and 50 Service attaches in place” as evidence that you are a mature customer managing your license spend – and therefore deserving of the best volume pricing on the base licenses you do buy.
- Incorporate Attach Usage into Future Planning: When planning expansions, new Dynamics 365 module rollouts, or adding users, always model the scenario with base and attach licenses appropriately. Forecast the number of new base licenses versus attached licenses that will be needed. This helps in budgeting and ensures you don’t accidentally over-commit to full licenses. For example, if rolling out Dynamics 365 Field Service to a group that already uses Sales, assume most will be attached. Only new individuals without a license will require new bases. This level of planning detail can prevent budget overruns and also impress Microsoft with your clarity, which might help in getting flexible contract terms.
- Stay Updated on Licensing Changes: Microsoft occasionally updates licensing rules, prices, or offers bundles that could affect your base+attach strategy. For instance, new bundled SKU offerings or promotions might appear. Always evaluate them against your current base and attach approach. In many cases, the custom mix-and-match via attach will be cheaper if you don’t need everything in a bundle. But if Microsoft, say, introduces a special bundle combining three apps for a flat price, do the math – sometimes such offers can be competitive. The key is to not blindly assume base+attach is always optimal; it is in most scenarios, but staying informed ensures you capture any new opportunities (or avoid any pitfalls from rule changes).
- Foster a Culture of License Optimization: Ultimately, make cost optimization part of the culture in your IT and procurement teams. Base vs attach licensing is one tactic under a broader mindset of optimization. Encourage teams to regularly question, “Is there a cheaper way to license this user without sacrificing needed functionality?” By treating Microsoft licensing with the same level of cost scrutiny as any other major expense, you’ll naturally catch things like missed attachment conversions or oversized license tiers. This culture, combined with specific knowledge such as the base-attach model, empowers your organization to continuously save money and reinvest those savings into high-value initiatives.
Adopting these practices will ensure that Dynamics 365’s flexibility translates into real financial benefit.
In summary, base and attach licensing is not just a licensing oddity to be aware of – it’s a strategic lever. Enterprises that weave this into their license management processes can free up significant budget while still equipping their users with all the tools they need.
FAQ – Dynamics 365 Base vs Attach Licensing
Q: What is the difference between a base license and an attach license?
A: A Base license is the standard, full-price license for a Dynamics 365 application that a user is given as their primary license. Every user must have at least one base license for their first app. An Attach license is a heavily discounted license for any additional Dynamics 365 app that the same user needs. The attached license grants the user the same capabilities in the second app as a standard full license would. Still, it costs significantly less because the user already possesses a base license. In short, the first app is base (full price), the second (or third, etc.) apps for that user are attached (add-ons at a lower price).
Q: Which license should be chosen as the base when a user needs multiple apps?
A: Always use the highest-priced app as the base license for a user who needs multiple Dynamics 365 applications. Microsoft’s licensing rules actually require that the first license (base) be the most expensive one the user uses. From a cost perspective, this maximizes your savings because you pay full price for the priciest app and then attach any cheaper apps at a discount. For example, if a user needs Dynamics 365 Finance (expensive) and Sales (less expensive), Finance should be the base and Sales an attachment. If two needed apps cost the same, you can pick either one as the base – just be sure one is base and the other attach, rather than accidentally buying both as standalone licenses.
Q: Can base vs attach be applied mid-contract?
A: Yes, in most cases, you can apply base vs attach licensing mid-term, though it might require some coordination. If you discover during your contract that certain users have been assigned multiple full licenses, you don’t necessarily have to wait until the contract ends to fix it. You can work with Microsoft or your licensing partner to convert a full license to an attach license for those users. This can be achieved through a process known as a true-up/true-down, or license reallocation. Often, at the annual true-up, you can reduce the count of a base license and add the equivalent attach license. In some licensing programs, you might be able to make the change immediately in the admin portal by purchasing a new attach SKU and dropping the redundant full SKU. Always communicate with your Microsoft rep to ensure compliance when making mid-term adjustments. The key point: you’re not locked into overpaying for the rest of the year – Microsoft allows license count adjustments, so you should optimize as soon as you identify an issue.
Q: How much can base vs attach save enterprises?
A: The savings can be substantial. For a single user, an attach license can be 60–80% cheaper than a full base license for the same app. So if one user needs two apps, instead of paying 100% + 100% (200%) of the cost, you might pay 100% + 20% (120%) of one app’s cost for both – effectively saving around 40% of what two full licenses would have cost. At scale, if you have hundreds of users with multiple app needs, the aggregate savings easily reach into six or seven figures over the course of a multi-year agreement. Enterprises have reported reducing their Dynamics 365 licensing spend by up to 30-40% by eliminating redundant full licenses and utilizing attachments effectively. The exact amount will vary based on the number of multi-app users and the price differences of the apps, but it’s one of the biggest single levers for cost reduction in Dynamics 365 licensing.
Q: What’s the most common mistake enterprises make with base vs attach?
A: The number one mistake is paying double for a multi-app user – meaning they assign two (or more) separate base licenses to one person instead of utilizing base+attach. This often occurs due to organizational silos or simply not being aware that attachments exist. The result is the company pays full price twice for the same user’s access, which is exactly what the attach model is meant to avoid. Another closely related mistake is failing to designate the correct base license (usually by error, assigning a cheaper app as the base and thus not attaching the costlier app). Both scenarios lead to needless overspending. In summary, failing to use the attach model when necessary is a significant mistake, whether due to duplicate licenses or incorrect configuration. The cure is spreading awareness and instituting governance so that whenever a user needs a second app, the first question asked is, “What’s their base license going to be, and can we attach this additional app to an existing license?” Keeping that mindset front and center will steer you away from common pitfalls and ensure you reap the cost savings that Microsoft built into the Dynamics 365 licensing system.
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