Dynamics 365 Base vs Attach Licensing Explained
Understanding Microsoft’s Dynamics 365 base vs. attach licensing model is crucial for any enterprise aiming to optimize costs. In Dynamics 365’s licensing scheme, Microsoft offers a built-in way to license multi-app users more economically.
However, this model is often misunderstood or overlooked. The result? Companies end up overpaying for licenses that could have been significantly discounted.
In this deep dive, we’ll unpack how base and attach licenses work and show how savvy CIOs, procurement leaders, and licensing managers can leverage this model as a major cost-saving lever. Read our ultimate guide to Microsoft Dynamics licensing and negotiations.
We’ll illustrate how to structure licenses for users who need multiple Dynamics 365 apps, highlight common mistakes (such as buying two full licenses for one person when an attachment would suffice), and provide a practical framework for using base vs. attachment licensing in ongoing governance and Microsoft negotiations.
Why Base vs Attach Licensing Matters
Licensing accounts for a significant portion of Dynamics 365’s total cost of ownership. Every user license contributes to recurring monthly fees, so inefficient licensing can quickly inflate your budget.
Microsoft’s base vs. attach model is meant as a cost-optimization tool for organizations – essentially a volume discount for users who need more than one Dynamics 365 application.
It matters because when used correctly, it can dramatically reduce license costs for those multi-app users.
On the flip side, if misapplied or ignored, enterprises can overspend by paying full price for each app per user.
In summary:
- Licenses drive significant cost: For many enterprises, software licensing (especially for large CRM/ERP suites like Dynamics 365) is a top budget item. Optimizing licenses directly lowers operating costs.
- Microsoft offers built-in savings: The base+attach structure is Microsoft’s built-in discount mechanism for multi-app users. It’s there to encourage adoption of multiple modules without doubling the price tag. When fully leveraged, it lowers the cost per user who needs multiple Dynamics 365 apps.
- Misunderstanding leads to overspending: If you don’t understand the difference between base and attach, you might assign every app as a full-price license. Enterprises that fail to use attached licenses end up paying far more than necessary. We’ve seen companies accidentally buy two or three separate full licenses for one person – a costly mistake that the attach model was designed to avoid.
In short, base vs. attach licensing matters because it’s one of the simplest ways to cut Dynamics 365 costs. It ensures you’re not paying twice for the same user. Next, let’s clarify exactly how this model works.
Read about Dynamics 365 License Audit: Step-by-Step Framework for Cost Optimization and Negotiation Leverage.
How Dynamics 365 Base vs Attach Licensing Works
The Dynamics 365 licensing model distinguishes between a “Base” license and an “Attach” license for full-use users.
These terms determine how you should license a single user who needs access to multiple Dynamics 365 applications:
- Base License: This is the primary license for a user – the first Dynamics 365 application you assign to them. Every user must have at least one base license, and it is always purchased at full price. Importantly, when a user needs multiple apps, Microsoft requires that their base license be the highest-priced app that the user will use. The base license unlocks the core platform rights (e.g., the underlying infrastructure entitlements) for that user. For example, if a user’s main role is in sales, you might assign the Dynamics 365 Sales app as their base license. If another user primarily works in finance, Dynamics 365 Finance could be their base license. The base license is essentially the foundation – think of it as paying full fare for the first product.
- Attach License: Once a user has a base license, any additional Dynamics 365 apps they need can be added on as attach licenses. An attach license is the same product and full functionality as a base license for that app – the only difference is price and eligibility. Attach licenses are heavily discounted compared to base licenses. They can only be purchased for a user who already has a qualifying base license (you cannot buy an attach license on its own). The idea is that if one person needs two or three Dynamics modules, you only pay full price for the first one; every subsequent app for that same user is at a reduced rate. Microsoft designed attach licenses because a single user can only utilize so much software – it wouldn’t make sense to charge them twice or three times the price if they’re using multiple, integrated apps. In practice, attaching licenses often costs only about 20–30% of the full price of the same app. They deliver the same capabilities to the user as a normal license for that app; you’re just rewarded with a discount for having that user on multiple Dynamics products.
To illustrate the pricing differential, suppose the list price of a certain Dynamics 365 app as a base license is $100 per user/month. The attached license for that same app might be around $20 per user/month for any user who already has another base license.
This means the user’s second app is 80% cheaper than it would be if bought standalone. Microsoft introduced this base/attach structure to encourage customers to adopt multiple Dynamics 365 apps by significantly lowering the marginal cost of additional apps for the same person.
A few key points to remember about how it works:
- Every user needs a base license first. You cannot have an attach license without a base. If an attached license is assigned and the user’s base license is ever removed, the attached license becomes invalid. The attachment is always “attached” to an active base license.
- Base vs attach is a pricing distinction, not a product difference. The attached version of (say) Customer Service is functionally identical to the base version of Customer Service. There are no feature cuts – it’s purely a billing construct. So you shouldn’t hesitate to use the attached, thinking they are “lesser” licenses; they are fully featured.
- The base should be the highest-priced app needed. This is both a compliance rule and a cost optimization tactic. Microsoft expects that if a user needs two apps with different prices, the more expensive one is the base license. This ensures Microsoft isn’t giving a bigger discount than intended. It also makes sense for you: you maximize savings by paying full price on the costliest app and getting cheaper attachments for the rest.
- Multiple attach licenses allowed: A single user can have several attach licenses if they need more than two Dynamics 365 apps. For example, one person could have a base license plus two attachment licenses for three different apps they use in their job. You only need one base per user; everything else is layered on as attachments.
In essence, the base license is your “first app” for a user, and attach licenses are a bundle of additional apps at a fraction of the price. Now let’s look at some concrete examples to see the impact on cost.
For more insights, read ” Dynamics 365 Renewal Negotiation Strategy: How to Secure Better Terms and Lower Costs.
Examples of Multi-App Users
To make this more tangible, consider a couple of common scenarios where a single employee needs access to two Dynamics 365 applications as part of their role.
We’ll compare the cost of licensing them without using the attach model (i.e., buying two separate base licenses) versus with the base+attach model.
- Sales + Customer Service User: Imagine a user who works in both sales and customer support – perhaps an Account Manager who also handles some client service issues. This person needs access to Dynamics 365 Sales and Dynamics 365 Customer Service modules. If you mistakenly purchased two full base licenses for them, you’d pay roughly $100 + $100 = $200 per month (assuming each app’s base license is about $100/user/month for the Enterprise edition). However, using base and attach, you would assign one as the base license (typically the one they use most or the higher-priced one; in this example, Sales and Customer Service actually have the same price). Say you make Sales the base at approximately $100, and then add Customer Service as an attachment for around $20 more. The total comes out to about $120 per month, instead of $200. That’s a 40% cost reduction for this user. Multiply that by, for example, 50 users in similar dual roles, and you’d be saving $4,000 per month (or nearly $50,000/year) just by smart licensing.
- Finance and Supply Chain User: Now consider a user in operations who requires both Dynamics 365 Finance and Dynamics 365 Supply Chain Management (SCM) to perform their job. These ERP modules are typically higher priced than the CRM ones. Let’s say a Finance or SCM-based license costs around $210 per user/month (these are robust enterprise apps). Buying both separately would cost $210 + $210 = $420 per month for one user. But with base/attach licensing, you would assign the more expensive (or either one, if they’re similarly priced) as the base. In this case, Finance and SCM are priced the same, at around $210, so you can choose one as the base for $210. Then the second app can be added as an attachment for roughly $30 more per month (attachment licenses for ERP apps are roughly one-seventh to one-sixth the price of a full license). That brings the total to approximately $240 per month, down from $420 per month. The company saves almost 45% on that user’s licensing. If you had 20 users requiring both Finance and SCM, this approach would save approximately $3,600 per month (over $40,000/year) compared to providing each user with two full licenses.
As these examples demonstrate, the savings per user can be substantial – often amounting to hundreds of dollars per user annually.
In larger deployments with many users needing multiple apps, the base vs attach model can easily save an enterprise six or seven figures over the course of a multi-year agreement.
The key is to ensure each user has only one base license, and any additional apps for that user are at the attach price. Next, we’ll explore some common pitfalls where organizations fail to realize these savings.
Common Mistakes in Applying Base vs Attach
Despite the clear benefits, many organizations misapply the base/attach model or overlook it altogether. Here are some of the most common mistakes and oversights to watch out for:
- Assigning multiple base licenses to one user: This is a classic error – a user ends up with two or more full-price Dynamics 365 licenses because the ‘attach’ concept was not applied. Often this happens out of habit or siloed purchasing (e.g., you expand Dynamics usage and a department buys a new license for a user who already had one from another department). If you see a single name with both “Sales” and “Customer Service” listed as “Base” licenses in your tenant, that’s a red flag. Over-licensing like this means you paid double when you could have paid a fraction of the price for the second app. The remedy is straightforward: one of those licenses should be converted to an attach license at the next opportunity (mid-term adjustment or renewal). Every user should have no more than one base license.
- Lack of governance/siloed license assignments: Many large enterprises have different teams or units handling their own licensing needs, resulting in inconsistent practices. One business unit might assign a Finance license to a user, while IT later assigns the same person a separate Supply Chain license, unaware of the initial license assignment. Without central oversight, you may unknowingly be issuing redundant base licenses. The mistake here is not having a centralized view or control of Dynamics 365 licensing. The result is often duplicate costs and missed savings. The solution is to institute governance: a central licensing administrator or process should review all Dynamics 365 user assignments to ensure compliance. This ensures that when a new license is requested for someone, you check what they already have. If they have a base, you add an attachment; if not, assign the appropriate base first. Effective communication between departments (or ideally, a single point of contact for all Dynamics licensing) prevents costly duplication.
- Choosing the wrong app as the base license: Another subtle mistake is not selecting the optimal base license when a user needs multiple apps. While Microsoft’s rule is the base must be the highest-priced app, some licensing admins might not realize this or might simply assign licenses in the wrong order. For example, if a user needs both a $210 app and a $100 app, and you, for some reason, made the $100 app the base, you cannot attach the $210 app to it (that attach would not be “qualifying” since the base is cheaper). You’d end up having to pay full price for both, or you’d be out of compliance. Even when apps are similarly priced, it’s wise to designate the one that’s most critical or most expensive as the base to maximize your discount on the second app. Misunderstanding this can lead to either compliance issues or leaving money on the table. The best practice is to always assign the priciest required app as the base for that user and attach the others to it. This way, you meet Microsoft’s requirements and get the highest possible savings.
In addition to the above, some organizations mistakenly think an attach license might have limited functionality (it does not – it’s fully functional) or they forget to remove an attach when a base license is dropped (which can cause compliance problems).
The overarching theme is that careful license management and education are needed to avoid these pitfalls. Next, we’ll examine ways to proactively optimize costs using a base-attach strategy as part of your licensing governance.
Cost Optimization Through Base vs Attach Strategy
To fully capitalize on the base vs attach model, enterprises should treat it as a core part of their licensing strategy.
Here are practical steps and policies to optimize costs using base and attach licenses:
- Establish a “base-first, then attach” policy: Make it an internal rule that if any user requires more than one Dynamics 365 app, the additional apps must be attached, not standalone licenses. Communicate this policy to all IT and procurement staff involved in license provisioning and administration. By standardizing this practice, you ensure no one accidentally orders a second base license for a user. Essentially, enforce one base license per user as a firm guideline.
- Centralize license management and reviews: Implement a governance process where a central team or licensing specialist oversees all Dynamics 365 user licensing. This person or group should have visibility into all users and licenses. Before approving any license purchase or assignment, they can check if the user already has a base license. Central governance helps prevent the silos and duplicate licensing we discussed. It also allows for organization-wide audits of license usage – for example, running reports to find any users with multiple full licenses (and then fixing those). Regular oversight is key to cost optimization.
- Use role-based licensing templates: Map out typical user roles in your organization and the Dynamics 365 apps they need. For multi-app roles (e.g., a Sales & Service role or a Finance & SCM role), define a standard license bundle that explicitly calls for one base and one attachment. For instance, you might document that “Sales+Service users get Sales Enterprise (base) + Customer Service (attach).” By planning license combinations, you minimize ad-hoc decisions and ensure consistency. This also makes it easier to forecast costs and identify where attach licenses should be used.
- Monitor usage and adjust: Keep an eye on how users are actually using the applications. If someone isn’t really utilizing that second or third app, you might reevaluate whether they need the attached license at all. Conversely, ensure that people who are assigned attach licenses still have their base license active at all times (to remain compliant). Periodically review license assignments versus user activity logs. This ongoing monitoring will help you optimize license allocation – turning off unneeded attach licenses saves money, and catching any mistaken full license assignments saves even more.
By institutionalizing these practices, enterprises can systematically reduce excess licensing costs. Base vs attach shouldn’t be an afterthought; it should be baked into how you plan and govern Dynamics 365 usage from day one.
Organizations that implement this approach have seen significant reductions in their Dynamics spend without compromising any user functionality – simply by eliminating duplicate payments for users with multiple app needs.
Using Base vs Attach in Negotiations with Microsoft
Beyond day-to-day governance, the base vs attach model can also be a powerful tool in your licensing negotiations with Microsoft.
When it comes time for renewal or a new Enterprise Agreement, leveraging the efficiencies of base+attach can improve your bargaining position:
- Lower your “perceived demand” for full licenses: If Microsoft’s sales team thinks you need 200 full licenses (because you have users in multiple apps), they might quote a very high renewal. Instead, make it clear from the start that your requirement is, for example, 100 base licenses and 100 attach licenses, not 200 base licenses. By doing so, you frame the deal around the discounted model. This signals to Microsoft that you are an informed customer who won’t over-buy. It can prevent them from over-counting your needs and also pressure them to give you the best pricing on those 100 base licenses, since you’ve minimized the count of high-cost licenses.
- Explicitly structure the quote as base + attach: When discussing pricing with Microsoft or a reseller, ensure they price your multi-app users correctly. For instance, if you need Dynamics 365 Sales and Customer Service for 500 users, the quote should be for “500 Sales (base) + 500 Customer Service (attach)” — not “500 of each at full price.” Microsoft reps should understand this, but it’s worth double-checking the paperwork. Insist that your agreement or proposal clearly shows the attached licenses at the reduced unit price. This avoids any confusion later and ensures the savings are locked in writing. It also helps avoid a scenario where someone mistakenly tries to bill you for two full licenses per user.
- Leverage attached savings as negotiation capital: You can use the existence of attached licensing to your advantage in negotiations. For example, you might say, “We plan to fully leverage the attach model to keep our costs down – otherwise we could not afford to roll out multiple Dynamics 365 modules.” This subtly reminds Microsoft that you have cost alternatives (in essence, that you won’t simply pay double for additional apps). Microsoft wants you to adopt more Dynamics 365 products, so please note that the attached pricing makes this feasible. In some cases, you could push for additional discounts on the base licenses by pointing out how much you’re investing across multiple products. The fact that you’re expanding usage (albeit at attach rates for some licenses) is still a commitment they value; use that to negotiate better terms on the overall package.
- Bundle the base/attach strategy into renewal talks: When renewing, come prepared with data on how many users are multi-app and how much you’re saving by using attaches. This demonstrates to Microsoft that you are proactive and will continue to optimize. You can then negotiate things like price lock guarantees for attach licenses (ensuring the discount stays in effect) or ask for promotional considerations (e.g. “throw in 50 free attach licenses for module X” if you’re buying a lot of bases for module Y). While attached licenses are already cheaper, everything is on the table in an enterprise negotiation – you might secure even better rates or additional capacity by demonstrating that your smart licensing practices are part of your cost baseline.
In summary, incorporating the base vs attach approach in negotiations underlines that your organization is cost-conscious and informed. It helps steer the conversation toward value and efficiency rather than focusing solely on raw volume.
Microsoft, recognizing that you will optimize internally, is more likely to come to the table with competitive pricing to ensure you continue expanding your Dynamics footprint (instead of, say, exploring third-party alternatives or limiting your use to fewer modules). Utilize the base/attach model as both a cost-saving measure and a negotiation tactic to secure the best possible deal.
Strategic Recommendations for Enterprises
To wrap up, here are some strategic recommendations for enterprise leaders to make the most of Dynamics 365 base vs attach licensing:
- Conduct a license audit before renewals: Before you enter any renewal or true-up, perform an internal audit of your Dynamics 365 user licenses. Identify any users who currently have more than one full (base) license or any anomalies in assignments. This audit will uncover base vs attach misalignments – for example, users who should be on an attach license but aren’t. Armed with this information, you can correct the issues (reassign licenses appropriately) and approach your renewal with a clear understanding of exactly how many base and attached licenses you truly need. It prevents you from renewing unnecessary licenses and strengthens your negotiating position with accurate data.
- Make base vs attach a core part of license governance: Treat the enforcement of the base/attach model as a key cost governance policy for Dynamics 365. This means training your licensing administrators, IT staff, and procurement managers on what base and attach licenses are and how to apply them. Include checks for base vs attach in your onboarding or provisioning workflows. For example, when a manager requests access to a new module for a user, the workflow should ask, “Does this user already have a Dynamics 365 license?” If so, ensure the new license is assigned as shown in the attachment. By incorporating this into your processes, you can consistently capture savings and avoid a drift back to old habits.
- Use attached license data in Microsoft discussions: Gather data on how many attached licenses you are utilizing and for which products. This information is useful not only internally but also in conversations with Microsoft. It demonstrates that you have optimized your current usage (so Microsoft isn’t going to sell you something you don’t need). It also allows you to discuss growth in terms of base and attach, e.g., “We plan to add 50 new users on Product A next year, who will all attach Product B.” Sharing this plan demonstrates to Microsoft that you have a deep understanding of your usage. It can lead them to offer targeted promotions or bundles aligning with your strategy (since they see you actively adopting multiple apps, they may incentivize that).
- Incorporate base/attach into forecasting and budgeting: When forecasting future Dynamics 365 needs (for example, if you’re rolling out a new module to a department), project your license counts using the base vs attach model from the start. This means if 100 people will get a second app, budget for 100 attachments rather than 100 more full licenses. By planning this way, you’ll ensure you commit to the correct license quantities and avoid overestimating costs. It also ensures that when you commit to Microsoft in a 3-year agreement, you don’t lock in more expensive licenses than necessary. Essentially, make the base and attach assumptions part of your long-term IT financial planning. This approach will yield more accurate (and usually lower) cost projections for Dynamics 365 expansion.
By following these recommendations, enterprises can maximize the cost benefits of base and attach licensing. It moves you from a reactive stance (cleaning up licensing mistakes after the fact) to a proactive stance where cost optimization is built into your Dynamics 365 adoption strategy.
Companies that do this treat license dollars as an investment to be managed wisely, rather than a static fee – and they routinely save 20-40% on their Dynamics 365 spend as a result.
FAQ – Dynamics 365 Base vs Attach Licensing
What is the difference between a base license and an attach license?
A base license is the standard, full-price Dynamics 365 user license for a given app – it’s the first license a user needs to access that application. An attach license is an additional user license for another Dynamics 365 app that the same person can use at a significantly discounted price (because they already have a base license). In essence, the base is your primary license, and attached licenses are inexpensive add-ons for any other apps the user may need. Both types grant the same features and capabilities for their respective app; the only difference is that an attach license has a lower cost and requires an existing base license in that user’s account.
Which license should be chosen as the base when a user needs multiple apps?
You should generally choose the highest-priced app that the user needs as their base license. Microsoft’s rules mandate that the first (base) license be the highest-value one if a user has multiple licenses. For example, if a user needs both Dynamics 365 Finance (expensive) and Dynamics 365 Sales (less expensive), you’d assign Finance as the base and Sales as the attachment. This not only ensures compliance with Microsoft’s qualifying criteria, but also maximizes your savings – you pay full price on the costliest app and get the cheaper app at an even further discount. If two apps are similarly priced, it often doesn’t matter which is base, but as a rule of thumb, pick the one the user spends most of their time in or the one that makes them eligible for all needed attach SKUs.
Can base vs attach licensing be applied mid-contract?
Yes, you can usually implement base/attach optimizations even mid-contract, though the process might vary depending on how you purchased the licenses. If you discover that a user has two base licenses, you don’t necessarily have to wait until the contract renewal to rectify the issue. In many cases, you can work with your Microsoft reseller or account team to adjust the licenses – for example, by converting one of the licenses to an attach SKU in the future, or by reducing a redundant license and purchasing an attach license in its place. If you’re on a subscription model (like Microsoft’s CSP or monthly billing), you might be able to drop the extra license that same month and add an attach license immediately. If you’re in an Enterprise Agreement with annual true-ups, you can at least plan the correction at the next true-up or renewal, so you’re not renewing the mistake. The key is that the licensing programs are usually flexible enough to allow adding attached licenses at any time (since they’re just additional subscriptions), and removing unnecessary licenses with proper notice. Always coordinate with your licensing provider to ensure the change is done correctly, but don’t feel “stuck” with two base licenses for a user for the entire contract term – it can be remedied.
How much can base vs attach save enterprises?
The savings can be substantial. For a single user who needs two apps, the license cost of the second app might drop by 60-80% when using an attached license. For instance, instead of paying $100 + $100 for two apps (total $200), you might pay $100 + $20 (total $120), saving $80 per month per user (a 40% total reduction). Now scale that up: if 100 users need a second app, that’s $80 * 100 = $8,000 saved per month, or ~$96,000 per year. If some users need three apps, the third app would also be at attach pricing, compounding the savings. Enterprises with large Dynamics 365 deployments have reported hundreds of thousands of dollars in annual savings by leveraging base vs. attach instead of buying everything at full price. The exact amount depends on the number of multi-app users and the mix of products. Still, it’s one of the highest-impact optimizations – often reducing overall Dynamics 365 licensing spend by 20% or more compared to a scenario with no attached licenses.
What’s the most common mistake enterprises make with base vs attach?
The #1 mistake is simply not using attached licenses when they should be used. In other words, companies pay for two (or more) full licenses for the same person because they didn’t implement the base/attach model correctly. This usually happens due to decentralized licensing decisions or lack of awareness – one team buys a Sales license for Alice, another team later buys her a Customer Service license, and nobody realizes she could have had one of them as an attachment. This oversight leads to unnecessary costs. Another common mistake is not auditing license assignments regularly, allowing these situations to persist unnoticed. In summary, failing to leverage the attachment structure – either due to ignorance or organizational silos – is the most costly licensing mistake with Dynamics 365. The good news is it’s easily avoidable once your team understands the base vs attach concept and you put in place the governance to enforce it.
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