401(k) Calculator 2026

What a 401(k) contribution really costs per paycheck

A $196.15 contribution every two weeks — 6% of an $85,000 salary — lowers the paycheck by $152.99, not $196.15. The contribution comes out before federal income tax, so the income tax on that $196.15 disappears; what it does not escape is Social Security and Medicare, because the IRS treats elective deferrals as wages for FICA. So each dollar saved costs 78% of take-home in a no-tax state, and in California, where the contribution escapes state tax too, 69%. At 10% the paycheck falls by $254.99 for a $326.92 contribution.

The cost per dollar depends on the marginal rate, which is why it changes with salary: on $45,000 a 6% contribution costs 88% per dollar, on $150,000 76%. Higher earners are paid more to save. The chart under the calculator draws the curve one percent at a time for your own salary and state.

The other number the calculator watches is the match. With a 50% match on the first 6% of salary, contributing 3% earns $1,275 a year from the employer and contributing 6% earns $2,550; the difference, $1,275, is an immediate 50% return that no investment offers. The calculator names the amount left on the table whenever the contribution is below the match cap.

The 2026 limits

Elective deferrals to a 401(k), 403(b) or 457 plan are capped at $24,500 for 2026, with an extra $8,000 from age 50 and — under SECURE 2.0 — $11,250 instead for people who are 60, 61, 62 or 63 during the year; at 64 the ordinary catch-up returns. The employer match does not count against the elective limit; the combined employee-plus-employer limit is much higher. The figures come from IRS Notice 2025-67 and the calculator caps the contribution at the limit for the age you enter.

IRA limits are separate: $7,500 a year ($1,100 more from 50), and a traditional IRA contribution stops being deductible between $81,000 and $91,000 of income for a single filer covered by a workplace plan. HSA limits are $4,400 self-only and $8,750 family, and an HSA contribution through payroll escapes FICA as well, which a 401(k) contribution does not.

Roth vs traditional on the paycheck

A Roth 401(k) contribution comes out after tax: the same $196.15 lowers the paycheck by the full $196.15 rather than $152.99, and in exchange the withdrawals in retirement are tax-free. The traditional contribution saves tax now at the marginal rate and pays it later at whatever rate applies then; the Roth does the reverse. The paycheck difference between the two — $43.16 every two weeks on this example — is exactly the income tax the traditional contribution defers.

The employer match is always traditional (pre-tax) even when the employee contribution is Roth, and both kinds count against the same $24,500 elective limit. Tick the Roth box in the calculator to see the paycheck under either.

Growth: what the projection does and does not know

The growth tab compounds your contribution and the match at the annual return you choose, adding both at the end of each year. At 6% a year, $85,000 with a 6% contribution and a 50% match on it reaches $604,795 in 30 years, of which $229,500 is money paid in and the rest is growth. Change the return to 4% or 8% and the final figure moves a great deal, which is the honest lesson: the return is an assumption, not a forecast, and the calculator says so next to the result.

Two things the projection deliberately ignores: salary growth (a raise usually raises the contribution) and the tax on withdrawal (traditional balances are taxed as income when taken out; Roth balances are not). It also assumes the match vests; many plans vest employer contributions over several years, and leaving before then forfeits the unvested part.

Why a 401(k) does not reduce Social Security or Medicare tax

IRS Publication 15 lists elective deferrals to a 401(k) as «taxable» for Social Security and Medicare while «generally exempt» from income tax withholding. The reason is that FICA wages are defined in the Social Security law, not the income tax law, and the deferral counts toward your future Social Security benefit; the tax follows the benefit. So a $200 contribution saves the 22%-bracket employee $44 of federal income tax and nothing of the $15.30 of FICA on that $200. Section 125 plans — health premiums, HSA, FSA by salary reduction — are the exception and reduce FICA wages too.

The three taxes on a paycheck, and why they behave differently

Federal income tax is progressive and starts from zero: the first $16,100 a single filer earns in 2026 is untaxed because that is the standard deduction, and the rate then climbs through seven brackets from 10% to 37%. It is the only line your W-4 changes. FICA is flat from the first dollar — 6.2% for Social Security up to $184,500 of wages and 1.45% for Medicare without limit — and no form changes it. State income tax is whatever your state decided: nothing in 9 states, one flat rate in 13, brackets in the other 29, and 11 states let a city or county add a line of their own.

On the $3,269.23 biweekly example above: $379.62 of federal withholding, $250.09 of FICA and $0.00 of Texas tax. Keeping them on separate lines is the point: a 401(k) contribution moves the first and third but not the second; a raise moves all three at different rates; the Social Security cap moves only the second. A single «taxes» figure hides which lever does what.

Pay frequency changes the number, not the pay

$85,000 a year is $1,634.62 a week, $3,269.23 every two weeks, $3,541.67 twice a month and $7,083.33 a month. Nothing about the tax changes, only the slice you see on payday — but the slice is what people budget from, and biweekly and semi-monthly are the pair that get confused: the biweekly paycheck is about 7.7% smaller, and in return two months a year contain three of them.

Frequency also affects withholding precision, because the IRS percentage method annualises each paycheck on its own. A monthly paycheck with a bonus in it is annualised twelve times over, a weekly one fifty-two times, which is why bonuses are usually withheld separately at a flat rate. Some years have 27 biweekly or 53 weekly paydays; the advanced panel of the paycheck calculator has both, because payroll software does.

Withholding is not your tax

Every federal line on a paycheck is an estimate your employer makes on your behalf, following your W-4 and IRS Publication 15-T; the tax itself is settled once a year on your return. On $85,000 with a 6% contribution, the year's withholding comes to $8,748 against a projected tax of $8,748: $0 short, which is owed at filing. Neither a refund nor a bill is a mistake by anyone; it means the W-4 on file did not describe the year exactly, and both are fixed on the W-4, not on the paycheck.

The three places the estimate goes wrong most: a second income in the household without the box in step 2(c) checked, so that both employers apply the full $16,100 standard deduction; a bonus withheld at the flat 22% when the marginal rate is something else; and untaxed side income with nothing on step 4(a). From 2026 there is a fourth, in the taxpayer's favour: the deductions for overtime premium pay and tips reduce the tax but not the withholding. The W-4 fixer turns the gap into the exact lines to change.

Reading the 401(k) on your pay stub and W-2

On the stub the contribution appears among the pre-tax deductions, and the federal taxable wages line is lower than gross by that amount while the Social Security and Medicare wages are not. On the W-2, box 1 (federal taxable wages) is smaller than boxes 3 and 5 (Social Security and Medicare wages) by the year's contributions, and box 12 carries the total with code D (401(k)), E (403(b)), G (457) or AA/BB (Roth). If box 1 equals box 3, nothing was deferred. The match is not on the W-2 at all; it appears on the plan statement.

What changed in 2026

The standard deduction is $16,100 single, $32,200 joint and $24,150 head of household; every bracket threshold moved up with inflation; the Social Security wage base is $184,500; the 401(k) elective limit is $24,500. Each is read from the document that sets it — IRS Revenue Procedure 2025-32, the SSA's contribution and benefit base, IRS Notice 2025-67 — and listed with its source under the calculator.

The bigger change is the set of new federal deductions: qualified overtime premium pay up to $12,500 ($25,000 joint), reported tips up to $25,000, and $6,000 more for each person aged 65 or over, all phasing out above $150,000 of income. None of them changes what an employer withholds, because Publication 15-T does not know about them; they reduce the tax owed at filing, which is why the calculators on this site show them in the «withholding vs what you owe» box rather than on the paycheck. The what changed in 2026 guide keeps the dated list, including state changes.

A worked example: $72,000 in California, paid every two weeks

Take $72,000 a year in California, paid every two weeks (26 paychecks), single, standard W-4, no pre-tax deductions. The gross per paycheck is $2,769.23. Federal income tax withholding, from the 2026 Publication 15-T percentage method, takes $269.62. Social Security takes 6.2% of gross, $171.69, and Medicare 1.45%, $40.15. California withholds $97.48 under its brackets and deductions. The net deposit is $2,190.29, 79.1% of gross; over the year that is $56,948 from $72,000, an effective rate of 20.9% on all taxes together. Every line is reproducible from the documents on the sources page, and the table below lists them in the order they appear on a stub.

Two things on that stub are not obvious from the totals. First, the federal line is withholding, not tax: the tables annualise this paycheck as if all 26 were identical, and the year's actual tax, $7,010, differs from the $7,010 withheld by $0, which becomes a refund in April. Second, Social Security and Medicare are the same fraction of every paycheck of the year, because the salary is under the wage base, and no form can change them; only Section 125 deductions reduce their base. The reading guide walks each line and names what it should equal.

Nearby salaries: what $52,000 to $107,000 leave in California

A raise or a job offer is rarely at the round number on this page, so here is the ladder around it: the same every two weeks paycheck at 6 salaries from $52,000 to $107,000, single, standard W-4, no deductions. The effective rate climbs from 17.7% to 26.7% across the range because federal income tax is progressive while FICA is flat; each extra $10,000 of salary leaves less than the last, and the pay raise calculator prices any step exactly. The salary after tax pages carry the full range, one page per amount.

Reading the ladder the other way answers the interview question: to take home $10,000 more a year in California takes a raise of roughly $13,648 in gross at this level, because the new dollars are taxed at the marginal rate rather than the average. The state column grows faster than the salary, since California's brackets rise with income; the FICA column grows in a straight line until the wage base. The gross-up calculator runs the reverse computation for any net.

The same paycheck under each filing status

Filing status is the one W-4 line everyone fills in, and it moves the federal line more than most people expect. On $72,000 in California, paid every two weeks, a single filer is withheld $269.62 per paycheck; married filing jointly (one income) $164.62, because the joint table doubles the standard deduction to $32,200 and widens every bracket; head of household $207.23, with its $24,150 deduction and its own brackets. Married filing separately uses the single table. California's own deductions and brackets follow the state’s own joint schedule, which is why the state column moves too. Picking «married» with two incomes and skipping step 2 is the commonest cause of an April bill; the W-4 guide covers the choice.

The last column shows why the status matters beyond the paycheck: the year's federal income tax on $72,000 is $7,010 single and $4,280 married filing jointly on one income, a difference of $2,730 that the W-4 status either delivers through the year or holds back for a refund. Head of household is the status most often missed by single parents, who leave $1,622 a year on the single table. FICA is identical in every row, since it has no status.

The whole year on $72,000: withholding, tax due, and the settlement

26 paychecks of $2,769.23 withhold $7,010 of federal income tax over 2026. The tax actually due on the return, with the $16,100 standard deduction and no credits, is $7,010, so the year ends with a refund of about $0 — the gap between the withholding tables' approximation and the exact computation. The marginal rate on the last dollar is 22%; the effective rate on all taxes together is 20.9%. Social Security applies to every paycheck of the year, because $72,000 is under the $184,500 wage base. The 2026 deductions for overtime premium and tips apply at filing to anyone with qualifying pay; they do not change these paychecks. California takes $2,535 for the year, 3.5% of salary.

Refund or bill: what the year settles

Withholding is a prepayment; the return computes the tax and returns or collects the difference. On $72,000 with these settings the year withholds $7,010 against $7,010 due, so the settlement is a refund of about $0. A refund is money lent to the Treasury at no interest for up to sixteen months; a bill is fine up to a point and penalised beyond it. The point is the safe harbour: withholding of at least 90% of this year's tax ($6,309 here) or 100% of last year's (110% above $150,000 of income) avoids the underpayment penalty, which is interest on each quarter's shortfall. These paychecks clear the 90% harbour on their own.

What makes the settlement move: credits the W-4 does not carry (the earned income credit, education credits, the 2026 overtime and tip deductions), which enlarge the refund; a second income, other income, or too many dependents on the form, which produce the bill; a bonus withheld at the flat 22% when the marginal rate is 22%, which over-withholds at this salary; and a change of job or a partial year, which annualises each paycheck wrongly. The W-4 fixer sets the lines that bring the settlement to zero, or to a chosen refund.

What deductions do to this paycheck

Deductions are where the same salary produces different paychecks. A 6% traditional 401(k) contribution — $166.15 per paycheck on $72,000, well under the $24,500 annual limit — reduces federal and state taxable wages but not FICA wages, so it costs $116.30 of take-home rather than its face value. A $150 Section 125 deduction for health premiums or an HSA reduces every base including FICA, and costs $93.53. A Roth contribution of the same 6% comes out after tax and costs the full amount now in exchange for tax-free withdrawals later. The table gives each case for this paycheck; the pre-tax deductions calculator runs any amount and the 401(k) calculator draws the whole curve.

The order matters on the stub as well as in the arithmetic. Section 125 items come off first and reduce the FICA wages line, which is why a health premium lowers the Social Security and Medicare figures by 7.65% of itself; the 401(k) comes off next and reduces federal taxable wages only. Both appear in the W-2: box 1 (federal wages) is gross minus both, boxes 3 and 5 (Social Security and Medicare wages) are gross minus the Section 125 items alone. An employer match, where there is one, is added on top of the contribution and never touches the paycheck; the compare two jobs tool values it.

What each W-4 line does to this paycheck

The federal line is the only tax on the stub that a form can change, and each step of the W-4 moves it by a predictable amount. One qualifying child on step 3 lowers withholding by $84.62 per paycheck — the $2,200 credit spread over 26 paychecks — taking the net to $2,274.91. Checking box 2(c) for a second job raises it by $178.34, because the checkbox table halves the brackets so that each job is withheld as if it earned half the household income. Extra withholding on 4(c) is dollar for dollar. Other income on 4(a) adds the tax on it at the marginal rate; deductions on 4(b) remove it. The table runs each case for $72,000 in California; the W-4 fixer computes the combination that makes the year's withholding equal the year's tax.

None of these lines changes the tax; they change when it is paid. Claiming a child that is not yours on step 3, or deductions you will not take on 4(b), enlarges every paycheck and produces the same amount plus a penalty in April. The lawful levers are the ones you are entitled to — the children you have, the deductions you will itemise, the second income you must account for — and the fixer applies exactly those. A new W-4 takes effect from the next payroll run after your employer receives it, and the year-to-date withholding already taken is not recomputed.

$72,000 in California against nine other states

Federal tax and FICA are the same everywhere; the state line is what moves. On $72,000 paid every two weeks, the nine states with no wage tax leave $2,287.77 per paycheck; California leaves $2,190.29, $97.48 less, or $2,535 over the year. Flat-rate states sit in between and their rate is the whole story; bracket states depend on the salary. Prices move more than taxes between most of these states, and the state pages carry the BEA price index beside the take-home; the state ranking sorts all 51 for any salary.

Two cautions before reading the table as a moving guide. The state taxes wages where the work is done, with the resident state taxing everything and crediting the work state, so a remote job does not change the column unless you change where you live — and five states apply a «convenience of the employer» rule that keeps taxing remote work done elsewhere. And the no-tax states collect the difference elsewhere: property tax in Texas and New Hampshire, sales tax in Tennessee and Washington. The no-income-tax guide and the local taxes guide cover both.

Common mistakes

Contributing below the match cap. The match is an immediate 50% or 100% return; on this example stopping at 3% forfeits $1,275 a year. Expecting the 401(k) to lower FICA. It does not. Treating the projected balance as a promise. It is an assumption about returns, chosen by you.

Reading the flat 22% on a bonus as the tax on it. It is withholding; the tax is your marginal rate. Budgeting from the wrong paycheck: biweekly and semi-monthly differ by about 7.7%. Claiming the same child on two W-4s, which under-withholds the household by the credit. Assuming a raise can push you into a bracket that leaves you worse off — in a progressive system it cannot. Forgetting the Social Security cap: above $184,500 the later paychecks are larger, and a budget built on January's paycheck is too tight for December's.