Pre-tax retirement savings shrink your taxable income, so each dollar saved costs you less than a dollar of take-home pay.
401(k) rate
Saved per year
Federal tax
Take-home
0%
$0
$2,620
$34,320
5%
$2,000
$2,380
$32,560
10%
$4,000
$2,140
$30,800
15%
$6,000
$1,900
$29,040
With state income tax
State tax depends on where you live. These rows show the effect of a flat rate on top of federal taxes; plug your own state's rate into the paycheck calculator.
About $34,320 for a single filer in a state with no income tax, based on 2026 federal brackets, Social Security and Medicare. That is $2,860.00 a month or $1,320.00 every two weeks.
What tax bracket is $40,000 in?
For a single filer, after the standard deduction the top dollars are taxed at 12%. The average federal income tax rate is much lower, 6.6%, because lower brackets apply first.
How much does a 401(k) save in tax?
Putting 10% ($4,000) into a traditional 401(k) lowers federal income tax by about $480 a year for a single filer, so take-home pay drops by less than the amount you save.