How a SEP IRA limit is worked out
A SEP IRA takes employer contributions only: up to 25% of pay, and no more than $72,000 in 2026. For a sole proprietor, pay is net earnings after half of self-employment tax and after the contribution itself, which works out to 20% of net earnings.
There is no salary deferral and no catch-up, which is why a Solo 401(k) usually allows more for the same income. A SEP is easy to open and has no annual filing, which is its appeal.
Most SEPs are set up on IRS Form 5305-SEP, which cannot be used in a year the business maintains another retirement plan. If you are adding a cash balance plan, the usual path is to replace the SEP with a Solo 401(k). See SEP IRA or cash balance plan.