The agency match is paid one pay period at a time, on the first 5% of basic pay you contribute in that period. If you reach the annual IRS limit before the last pay period of the year, your contributions stop, and so does your match for every remaining period. Reaching the limit in October can quietly cost you hundreds of dollars in free money. This calculator finds the even per-pay-period amount that reaches your 2026 limit in the final pay period, so you capture the full match all year.
This calculator runs entirely in your browser. Nothing you enter is saved, transmitted, or seen by ThriftTrading. 2026 limits per IRS Notice 2025-67 and tsp.gov. Match math assumes FERS or BRS matching: 1% automatic plus up to 4% matched per pay period when you contribute at least 5% of basic pay.
Your agency's contributions come in two parts. The automatic 1% arrives whether you contribute or not. The matching portion, up to another 4% of basic pay, is earned pay period by pay period, and only in periods where you contribute. There is no year-end true-up in the TSP. A period with no contribution is a period of matching you never get back.
If you are under 50 and hit the $24,500 limit in pay period 20, the system simply stops your deductions, and pay periods 21 through 26 each forfeit 4% of your per-period basic pay in matching. If you are 50 or older, front-loading is more forgiving: once you pass the regular limit, contributions spill over automatically toward your catch-up limit and the match keeps flowing until you reach the combined limit for your age group. The calculator above accounts for this.