The plan year is set in the plan document. Most one-person plans use the calendar year, matching the business's tax year, which keeps the deadlines lined up. Each plan year has its own valuation, contribution range, 415(b) test and, once assets pass $250,000, Form 5500-EZ.
A new plan can be adopted after its first plan year ends. Under IRC 401(b)(2), a plan adopted by the business's tax return due date, including extensions, can be treated as adopted on the last day of the year. That is why a plan for 2026 can still be opened after December 31, 2026.
| Date | What is due |
|---|---|
| August 2, 2027 | Form 5500-EZ due (if required) |
| September 15, 2027 | Minimum required contribution due |
| October 15, 2027 | Last day to adopt the plan |
| October 15, 2027 | Last day to contribute for a 2026 deduction |
| October 15, 2027 | Form 5500-EZ due with an extension (if required) |
See cash balance plan deadlines or look up your own dates with the deadline calculator.