Exchange 2016 EOL Oct 14, 2025: Budget & Support Guide

The Date That Should Be in Your Budget Draft Now

Microsoft Exchange Server 2016 Cumulative Update 23 Security Update 22 (CU23 SU22) — build 15.1.2507.69 — will reach end of life (EOL) on October 14, 2025. That is roughly 13 months from today, which means it falls squarely in the next fiscal year for most organizations. The extended support phase ended October 13, 2020, so this is the final cutoff: after October 14, 2025, Microsoft will no longer provide security patches, hotfixes, or technical support for this version.

If you are building a budget for FY2026 (or the fiscal year that covers late 2025), this line item needs to be on your list now. Waiting until the EOL is six months out will compress your planning cycle — and that often leads to rushed decisions or unplanned expenditure.

What the EOL Date Actually Means

• No more security updates. Any newly discovered vulnerabilities in Exchange 2016 after October 14, 2025, will not be patched by Microsoft. For compliance-driven industries (finance, healthcare, government), this can be a hard blocker.
• No more non-security hotfixes. If a bug appears in the product that impacts your environment, Microsoft will not produce a fix.
• No vendor support calls. Even with an active Software Assurance agreement, support for this specific build ends at that date.

This is not an LTS (long-term servicing) release, so there is no extended patch window beyond the published end date.

The Upgrade Path: What It Typically Costs and How Long It Takes

Migrating from Exchange 2016 to Exchange Server Subscription Edition (SE) — or to Exchange Online — is a multi-phase project for any mid-to-large organization. The rough steps usually include:

1. Inventory and discovery — assessing mailboxes, public folders, connectors, and third-party integrations (2–4 weeks).
2. Lab environment setup and testing — standing up a pre-production Exchange SE or hybrid tenant, running migration tests (4–8 weeks).
3. Production migration — moving mailboxes, configuring mail flow, decommissioning the old servers (4–12 weeks, depending on scale).
4. Post-migration validation and cleanup — ensuring no data loss, verifying client connectivity, removing old endpoints (2–4 weeks).

For a typical organization with 500–2,000 mailboxes, this timeline lands at 3 to 6 months if everything runs smoothly. If your environment has customizations, complex compliance requirements, or limited internal bandwidth, that timeline can stretch to 9 months or more.

That is why starting the budget conversation now is critical: the migration timeline alone may push you past the EOL date if you wait until mid-2025.

Why Many Teams Can't Migrate in Time

• Internal capacity. Most IT teams already have a full project load. A full Exchange migration often requires dedicated staff or external consultants, both of which have lead times.
• Vendor roadmap uncertainty. Microsoft has not yet announced a long-term release date for the next on-premises Exchange version after SE. Some organizations hesitate to invest in a migration to a product that may itself have a short lifecycle.
• Third-party dependencies. Some legacy line-of-business applications, archiving tools, or email routing appliances only work with specific Exchange versions. Upgrading can force a parallel upgrade of other systems.
• Budget cycles. If your fiscal year starts in July or October 2025, the EOL date will hit before you have had time to execute a migration plan that was only approved in the new year.

Comparing Your Options: Migration vs. Extended Support vs. Third-Party Support

Option	Typical Cost (per year for 1,000 mailboxes)	Key Consideration
Full migration to Exchange Online / SE	$40,000–$80,000 (one-time, plus ongoing subscription costs)	Best long-term solution, but requires 3–9 months of project time.
Vendor extended support	Not available for Exchange 2016 after October 14, 2025. Microsoft ended the extended support phase in October 2020.	Not a viable path.
Third-party support (like 3rd Party Support)	Roughly 50% less than a full migration per year	Extends the life of Exchange 2016 with security patches and technical support. No migration project needed. Ideal as a bridge or long-term solution.

Note: The migration cost above is a one-time capital expense. Third-party support is an operational expense — it can sit in your annual maintenance budget without requiring a large project outlay.

For many organizations, the practical choice is to use third-party support to cover the post-EOL period, while deferring the migration to a later budget cycle or when the vendor roadmap becomes clearer.

What to Put in Your Budget Request Now

When you draft next fiscal year's budget, include three line items so you have flexibility:

1. Third-party support for Exchange 2016 CU23 SU22 — as a baseline for continuing operations past October 2025.
2. Migration project estimate — a separate, contingent line item covering the cost of upgrading to Exchange SE or migrating to Exchange Online. This can be flagged as "if approved, project timeline extends across Q2–Q4."
3. Security compliance buffer — a small fund for any urgent patching or compliance review if the migration timeline slips.

Submitting a budget request today that includes third-party support as a known cost — rather than scrambling for emergency funds six months from now — positions you as a proactive planner.

Get a Third-Party Support Quote First (Before Any Renewal Talks)

Before you enter renewal discussions with Microsoft or start pricing a full migration, get a benchmark: a third-party support quote for Exchange 2016. That number gives you a concrete "do nothing" cost to compare against the migration price. It also gives you leverage: if you can demonstrate that staying put with third-party support is cheaper and safer, you may push the migration decision to a later, less pressured budget cycle.

We can provide that quote quickly — just contact our team with your environment details (number of servers, mailbox count, current CU level). You will have a number in hand before you write the final budget line.

Resources

• Microsoft software lifecycle page on our site
• Lifecycle source for Exchange 2016

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Bottom line: Exchange 2016 CU23 SU22 end of life is October 14, 2025. The budget you write this year will determine whether your team is running securely — or scrambling — when that date arrives.