Somewhere around your 50th birthday, the tax code quietly raises your retirement savings limit — and most people never notice. In 2026 the regular 401(k)/TSP deferral limit is $24,500, but workers 50 and older can add a catch-up contribution of $8,000, for a total of $32,500 sheltered from federal income tax.
Why it is worth more than it looks
Pre-tax contributions dodge your marginal bracket, not your average rate. A filer in the 22% bracket who maxes the catch-up saves $1,760 in federal tax that year — plus whatever their state would have taken. The paycheck shrinks by noticeably less than the contribution, because the tax savings subsidize part of it.
That is the mental model to steal: a $308-per-paycheck catch-up contribution does not cost you $308 of take-home. It costs you $308 minus the tax that contribution no longer triggers.
Fixed dollars beat percentages here
Catch-up elections are usually made as a fixed dollar amount per paycheck, not a percentage — which is exactly why our calculator lets you choose either. Turn on the 50+ toggle, enter the catch-up as a per-paycheck amount, and watch how little your net pay actually moves. Most people who run the numbers discover they could have afforded the catch-up years ago.