Cash Balance Plan Deadlines
A new cash balance plan can be adopted and funded as late as the business's extended filing deadline and still be deducted for the prior year. This reference lays out that window and every other date a plan year runs on: safe-harbor timing, amendments, valuation, minimum funding, and Form 5500.
Reviewed by Alexander Tecle, MBA, MS Taxation
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Three clocks. Different decisions.
Adoption
When must the plan be established?
Funding
When must money reach the plan?
Filing & notices
Which returns and participant communications are due?
One deadline does not replace another. Match each date below to your plan and tax year.
| What | Deadline | Notes |
|---|---|---|
| Adopt a NEW plan for last year | Your tax-filing deadline, including extensions | SECURE Act retroactive adoption — employer-funded benefits only |
| 401(k) employee deferrals | Through final payroll of the year | Not retroactive for payroll deferrals (one exception: SECURE 2.0 §317 lets an owner-only sole proprietor make first-plan-year deferrals up to the unextended filing deadline); otherwise the one piece still tied to December |
| Fund contributions and deduct them | Generally by the return's extended due date | Deduction timing under IRC 404(a)(6) |
| Defined benefit minimum funding | 8½ months after plan year end (Sept 15) | The hard funding backstop for an ongoing plan |
| Form 5500 filing | Last day of the 7th month after plan year end (July 31) | Extendable to Oct 15 with Form 5558 |
| Start a NEW safe-harbor 401(k) for this year | Oct 1 (the first plan year must run at least 3 months) | A 3% nonelective safe harbor can also be added retroactively up to 30 days before year end, or at 4% by the end of the following year (SECURE Act) |
| Safe-harbor notice (matching designs) | 30–90 days before the plan year begins (Dec 1 at the latest) | Nonelective 3% designs no longer require the annual notice |
| Discretionary plan amendments | Last day of the plan year (Dec 31) | An amendment adopted within 2½ months after year end can be treated, for funding, as in effect on its first day (IRC 412(d)(2)) |
| Actuarial valuation and AFTAP certification | Valuation as of a date in the plan year; AFTAP certified by Oct 1 | The valuation sets the contribution range; a late AFTAP is presumed underfunded and benefit restrictions apply (IRC 436) |
| SECURE 2.0 required plan amendment | Dec 31, 2026 for most calendar-year plans | Per IRS Notice 2024-2; governmental and collectively bargained plans have later dates |
Calendar-year illustration; weekend/holiday rollovers and fiscal-year sponsors shift specific dates. Confirm your plan's dates with your administrator each year.
Cash balance planning runs on a small number of dates: when a plan must exist, when money must arrive, and when filings are due. The SECURE Act reshaped the first of these in owners' favor, since a plan can now be adopted after year-end for the prior year, which turned pension planning from a December scramble into a tax-season decision.
The calendar below uses a calendar-year plan and tax year (the common case). Fiscal-year businesses shift the same rules to their own year-end; your administrator maps the specifics.
On this page
Calculators
The calendar at a glance
For a calendar-year business sponsoring a calendar-year plan:
- Jan 1 — Plan year begins; valuation date for most plans
- Mar 15 — Unextended S-Corp and partnership returns due; an extension moves adoption, funding, and deduction to Sep 15
- Apr 15 — Unextended sole-proprietor and C-Corp returns due; extended to Oct 15
- Jul 31 — Form 5500 due (Form 5558 extends it to Oct 15)
- Sep 15 — Minimum funding backstop; extended S-Corp and partnership returns, the last day to adopt and fund for the prior year on extension
- Oct 1 — Last day to start a new safe-harbor 401(k) for the year; AFTAP certification due
- Oct 15 — Extended Form 5500; extended individual and C-Corp returns, the last day for retroactive adoption on extension
- Dec 1 — Latest safe-harbor notice for a matching design (30 days before the plan year)
- Dec 31 — Employee deferrals through final payroll; discretionary amendments; plan year ends
Safe-harbor 401(k) and amendment dates
Two more sets of dates matter for the combined design. A new safe-harbor 401(k) has to be in place by October 1 for a calendar-year start, because the first plan year must run at least three months (26 CFR 1.401(k)-3). Matching-formula safe harbors also need a participant notice 30 to 90 days before the plan year begins. The SECURE Act eased the nonelective side. A plan can be amended to add a 3% nonelective safe harbor up to 30 days before the plan year ends, or at 4% up to the end of the following plan year, and nonelective designs no longer require the annual notice.
Amendments follow their own calendar. Discretionary changes are adopted by the last day of the plan year they apply to, and an amendment adopted within 2½ months after the year ends can be treated for funding purposes as in effect on the first day of that year (IRC 412(d)(2)), which is how a benefit increase can absorb surplus after the fact. Separately, the plan document must be amended for SECURE 2.0 and related law changes by December 31, 2026 for most calendar-year plans sponsored by private employers, the deadline set in IRS Notice 2024-2; your administrator tracks the restatement.
The valuation has a date too. The actuary values the plan as of a date in the plan year (the first day for most plans; small plans may use the last day), and the AFTAP, the adjusted funding target attainment percentage, is certified by the first day of the tenth month, October 1 for calendar-year plans. Without a timely certification the plan is presumed underfunded and IRC 436 restrictions on lump sums and accruals apply until it is certified.
Using the retroactive window
The calendar allows a useful pattern. A business finishes a big year, sees the tax bill in February, adopts a cash balance plan by its extended filing deadline effective for that closed year, funds it, and deducts the contribution against the year that produced the profit. The trade-off for waiting is that census gathering, plan drafting, and funding all stack into tax season, so the comfortable version of this move starts the design conversation by early spring rather than October.
Ongoing-plan rhythm
Once the plan exists, the year settles into a rhythm. Administration exists so that these dates are watched by someone whose job it is; that service is what you're buying alongside the design.
Early in the year: the actuary's valuation sets the contribution range, and the AFTAP is certified before benefit restrictions would otherwise apply.
By the September backstop: fund the certified contribution; most owners fund with their tax filing.
Summer, or October on extension: the Form 5500 files.
On the plan's schedule: participant statements and required notices, including any safe-harbor notice before the next plan year.
The deadline that ends plans badly
Missing the minimum-funding backstop is the costly one: it triggers an excise tax and, uncorrected, threatens qualification. It is also almost always a symptom rather than a surprise: profits changed and nobody amended the plan in time. If a required contribution looks unaffordable, the moment to call the actuary is when you first suspect it, while amendment and freeze options are still open.
Frequently asked questions
Can I still set up a cash balance plan for last year?
Usually, yes — the SECURE Act lets an employer adopt a new plan up to its tax-filing deadline including extensions, effective for the prior year, with employer-funded contributions deducted for that year. Employee 401(k) deferrals through payroll cannot be made retroactively (the one exception is SECURE 2.0 §317, which lets an owner-only sole proprietor make first-plan-year deferrals up to the unextended filing deadline).
When does my contribution have to be paid?
For deduction purposes, generally by your return's extended due date. Ongoing plans also face the minimum-funding backstop 8½ months after the plan year ends — September 15 for calendar-year plans.
When is the Form 5500 due?
The last day of the seventh month after the plan year ends (July 31 for calendar-year plans), extendable to October 15 by filing Form 5558. Your administrator prepares and tracks it.
Is there any reason not to wait until tax season?
Only practicality: design, census work, and documents take real calendar time, and an extension leaves little room. Starting the conversation by early spring keeps the retroactive window comfortable instead of frantic.
When is the SECURE 2.0 plan amendment due?
For most calendar-year plans sponsored by private employers, December 31, 2026, per IRS Notice 2024-2; governmental and collectively bargained plans have later dates. The amendment is a document restatement your administrator prepares, and the plan must have operated under the new rules from their effective dates in the meantime.
Sources
- IRC §404 — deduction limits for employer contributions (opens in a new tab)
- IRC §412 — minimum funding standards and 412(e)(3) fully insured plans (opens in a new tab)
- IRC §430 — minimum required contributions for single-employer plans (opens in a new tab)
- IRC §436 — funding-based benefit restrictions (AFTAP) (opens in a new tab)
- 26 CFR 1.401(k)-3 — safe harbor 401(k) requirements and notice timing (opens in a new tab)
- IRS Notice 2024-2 — SECURE 2.0 guidance, including plan amendment deadlines (opens in a new tab)
- IRS — About Form 5558, extension of time to file (opens in a new tab)
- IRS — Form 5500 corner (opens in a new tab)
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This guide is educational and is not individualized tax, legal, or investment advice. Contribution limits and tax rules change annually and depend on your specific situation; figures are illustrative. Consult a qualified professional before acting.