Before You File: Tax-Smart Retirement Contributions You Can Still Make for Last Year

Well-timed employer contributions can still reduce 2025 taxable income and strengthen owner retirement savings. To ensure you maximize your opportunities for tax-savvy retirement savings, getting your CPA and RPC (TPA) on the same page to review opportunities for last minute 2025 contributions is key.

Key questions to ask your CPA to make sure you’re on top of what’s possible for your 2025 plan year before you file:

How much can I contribute now, and have it be treated as a contribution for last year?
What is our tax return due date for 2025, and are we extending?
If we extend, does that extend the deadline for deducting employer contributions intended for 2025?
If we already filed, do contributions funded now become a 2026 deduction automatically, or do we have options to include them in 2025 retroactively?
Are there entity-specific constraints on how plan compensation is determined for owners?
If the business is a sole proprietorship or taxed as a partnership, are there still opportunities to make owner employee 401(k) deferrals after year end based on tax filing timing?
Are we close to any contribution caps or compensation caps that could change our maximum allowable amount for 2025?
If we have a DB or cash balance plan, have we satisfied minimum funding expectations for the plan year?

For many plans there is still room to act. Let’s review the questions above from a general standpoint – be sure to consult your RPC (TPA) and CPA to find out where you and your business currently stand.

What is typically locked once the year ends

Employee salary deferrals, the amounts withheld from paychecks, are generally a closed door after year end because they require an active election and payroll withholding during the year. If you did not set them up in 2025, you cannot retroactively create them in 2026.

For certain business structures, including sole proprietors and owners taxed as partnerships, the timing rules around owner compensation can allow employee 401(k) deferrals to still be made after year end based on the tax filing timeline. Your CPA and TPA should confirm how these rules apply to your entity.

What may still be available

Employer contributions often have a longer runway. Depending on plan provisions and tax timing rules, a business may be able to:

Determine a 2025 profit sharing contribution after year end
Finalize certain employer match or nonelective contributions after year end
Fund a 2025 cash balance or defined benefit plan contribution during the tax filing period

Important dates in March and April 2026

For calendar-year entities, March and April are important because they define the filing deadline and extension decisions that often shape the final employer contribution window:

S corporations and partnerships commonly face a mid-March filing deadline
C corporations and individuals commonly face a mid-April filing deadline

If you extend your return, the contribution window for certain employer contributions can extend as well, but only if your plan terms and documentation align with that strategy.

Potential pitfalls to be aware of:

You can fund a contribution and still have the deduction land in a different year than you intended if the contribution is characterized incorrectly.

Key 2025 vs 2026 limits

Even though it is 2026 now, if you are making contributions intended for the 2025 plan year or the 2025 tax year, you are operating under the 2025 limits.

401(k) Elective Deferral: $23,500 (2025) vs. $24,500 (2026)
Overall DC Contribution (excluding catch-up contributions): $70,000 (2025) vs. $72,000 (2026)
Compensation Cap: $350,000 (2025) vs. $360,000 (2026)
Catch-Up (Age 50+ Regular Catch-Up): $7,500 (2025) vs. $8,000 (2026)

This matters most when owners are maxing out contributions, when compensation is near the cap, or when a DB or cash balance plan is paired with a 401(k) profit sharing plan.

What you can still do now, by plan type

401(k) with profit sharing

If your plan permits it, you may still be able to finalize and fund a 2025 employer profit sharing contribution during the tax filing window. This can materially change taxable income without changing payroll.

Confirm how the contribution will be treated (2025 vs 2026), eligibility and allocation, and the deposit timing your plan requires.

Employer match or nonelective contributions

If you have a match or a nonelective contribution, you may have flexibility to fund after year end, depending on plan terms. Some plans are written with stricter deposit expectations than the outer tax rules. Your TPA (RPC) should confirm these.

Cash balance and traditional defined benefit plans

If you sponsor a cash balance plan or a traditional DB plan, you already know these plans are built on structure.

Funding is calculated annually by your actuary
There is typically a minimum required contribution
Missing the minimum can trigger excise taxes, and the shortfall does not simply disappear, it compounds into future years

In practice, many cash balance and defined benefit plans are funded during the following tax season, meaning contributions for the 2025 plan year are frequently funded in 2026 during the tax filing window.

For sponsors running a DB or cash balance plan alongside a 401(k), the deduction conversation gets more technical, especially when the same participants benefit under both plans. Coordination is key so you do not learn about a limitation after money is already in motion.

Insights for CPAs

If you are a CPA advising plan sponsor clients, March is a busy time of year. The fastest way to add value is to separate “what can still be funded” from “what can still be deducted for last year,” then confirm timing and documentation before deposits are initiated.

Here are the core items to validate, in a general sense:

Confirm the contribution type and intended year. Profit sharing, match, nonelective, and DB funding are not interchangeable. Each has its own operational rules and practical documentation needs.
Confirm the sponsor’s filing strategy early. If the sponsor is extending, confirm whether that extension is being relied on for contribution timing, then confirm the plan’s terms support that approach.
Validate compensation inputs. Entity type and owner compensation structure can affect contribution modeling, especially for owner-heavy plans.
Confirm the correct year’s limits. If it is a 2025 contribution, use 2025 limits, even though funding occurs in 2026.
Request a quick allocation preview from the TPA before money moves. This prevents rework if eligibility or allocation assumptions are off.
For DB and cash balance plans, confirm minimum funding status. That is a compliance requirement, not just a tax planning lever.

FAQ

Can I still make a retirement plan contribution for 2025 in 2026?

Often yes for certain employer contributions, but generally no for employee salary deferrals that were not elected during 2025. Certain business structures, such as sole proprietors or businesses taxed as partnerships, may still have flexibility for owner deferrals depending on tax filing timing.

What contribution types are most commonly funded after year end?

Employer profit sharing contributions are the most common. Depending on plan terms, certain match or nonelective contributions can also be funded after year end. Cash balance and traditional defined benefit plan contributions are also frequently funded during the following tax season for the prior plan year.

If I extend my business return, does that give me more time to fund employer contributions for 2025?

In many cases, extensions can preserve the deduction window for employer contributions intended for the prior year, but plan terms and documentation still matter.

What happens if a DB or cash balance plan is underfunded?

Missing minimum funding can trigger excise taxes and can create a funding shortfall that carries forward into future years.

Which limits apply if we are funding 2025 contributions during the 2026 tax season?

The 2025 limits apply because the contributions are for the 2025 plan year and tax year, even though the funding is occurring in 2026.

For a review of what is still possible for your 2025 plan year before you file, your Retirement Plan Consultants at Nydia can coordinate the plan-side mechanics so your CPA can finalize your tax outcome with confidence.