Paycheck Calculator

Yes — and a paycheck calculator that doesn’t ask for pre-tax deductions is functionally useless. Pre-tax 401(k) and HSA contributions don’t just trim a few dollars; they restructure the entire withholding calculation by reducing the wages that federal and state income tax look at. The order of operations matters: gross pay first, then pre-tax deductions, then federal/state income tax on the reduced wages, then FICA (which uses its own wage base), then post-tax deductions, then net.

The 2026 401(k) elective deferral limit is $24,500. If you’re 50 or older, you get an $8,000 catch-up bringing your personal limit to $32,500. If you’re between 60 and 63 and your plan adopted the SECURE 2.0 super catch-up, you can go to $35,750. A paycheck calculator should let you enter either a dollar amount per check or a percentage of gross. A 10% contribution on a $5,000 bi-weekly check removes $500 from federal taxable wages before withholding runs, which at the 24% marginal bracket saves about $120 in federal tax that pay period — on top of the $500 going into your 401(k). Same goes for state tax in any state that conforms to federal treatment of 401(k) contributions, which is most of them. Pennsylvania is the famous exception: PA taxes 401(k) contributions at the time you make them, then doesn’t tax the distributions in retirement. A paycheck calculator that doesn’t know it’s a Pennsylvania check will get the state line wrong.

Roth 401(k) contributions don’t reduce taxable wages. Same dollar limit ($24,500 + catch-ups), same contribution mechanics, but the money is taxed before going into the account. Some paycheck calculators conflate Roth and traditional 401(k) deductions, which produces a wrong number on both the federal tax line and the take-home line. Always check which one the tool defaults to. We see this trip people up — especially actors and freelancers who file W-2 work alongside Schedule C, where the rules and the calculators are different. A Roth 401(k) deduction is still a real reduction in net pay; it just isn’t a reduction in taxable wages.

HSA contributions through payroll get treated even better than 401(k) contributions. A payroll-deducted HSA is exempt from federal income tax, state income tax (in most states), AND FICA. That triple shelter is unique. If you put $300 into your HSA from a bi-weekly check, you save the marginal federal rate plus 7.65% in FICA plus your state rate. For a New York City employee in the 24% federal bracket, that’s about 24% + 6.85% NY state + ~3.876% NYC city + 7.65% FICA = roughly 42% combined savings on the contribution. The 2026 HSA limit is $4,400 for individual coverage and $8,750 for family, with a $1,000 catch-up at age 55+.

HSA contributions made outside payroll — meaning you deposit money directly to the HSA bank account — only get the federal and state income tax break. FICA still applies. This is why we tell every client with a high-deductible health plan: contribute through payroll, not after the fact. The FICA savings alone make it worth the friction of filing the HR paperwork to set up the payroll deduction. A paycheck calculator should clearly mark which HSA route you’re using, because the math is different by 7.65%. We’ve seen people use a generic paycheck calculator that assumed payroll-deducted HSA when their actual contributions go through the bank, and they think they’re saving more than they are.

Don’t forget the other pre-tax lines: traditional pre-tax health, dental, and vision premiums (Section 125 cafeteria plan elections); dependent care FSA up to $7,500 per household in 2026 ($3,750 married filing separately); healthcare FSA up to $3,400; transit and parking benefits at $340 per month each in 2026; qualified commuter benefits in NYC and other transit-heavy cities; group term life insurance up to $50,000 of coverage; and adoption assistance up to $17,670 in 2026. Each one reduces your federal taxable wages and most reduce your FICA wages too (group term life is the main exception above $50,000). A serious paycheck calculator gives you a row for each category instead of lumping them into a single “pre-tax deductions” field. The aggregation hides errors and makes it impossible to audit your pay stub against the calculator output.

The other thing a paycheck calculator should expose: the order in which contributions hit the wage base for Social Security. Social Security tax (6.2%) caps at $184,500 of wages in 2026. Once you cross that cap, your bi-weekly check gets bigger because the 6.2% line disappears for the rest of the year. A pre-tax 401(k) contribution reduces federal and state taxable wages but does NOT reduce Social Security wages (which include the elective deferral). So a high earner front-loading 401(k) contributions hits the Social Security cap later than they otherwise would, but reaches it the same calendar year regardless. Medicare (1.45%) and Additional Medicare (0.9% above $200,000 from a single employer) have no wage cap. A calculator that shows the Social Security cap impact mid-year is useful for cash-flow planning — most calculators don’t.

Order of pre-tax stacking is worth knowing too. Section 125 cafeteria plan deductions (health, dental, vision, FSA, HSA) come out first, before FICA. Traditional 401(k) deductions come after FICA but before federal/state income tax. That’s why a $300 HSA contribution and a $300 traditional 401(k) contribution don’t save the same amount in tax — the HSA contribution also saves the 7.65% FICA.

If you’re tuning your 401(k) and HSA together against a target take-home, our helpful guides have a walkthrough on the order in which to fund retirement accounts — HSA first if you qualify, then 401(k) up to the employer match, then back to the HSA to the family limit, then back to the 401(k). For business owners running their own payroll, our business owners hub covers the S-corp wage-vs.-distribution split that changes the entire FICA picture and lets owners shift income out of the FICA base entirely.

This question lands in our inbox every January and every time someone gets a new job. The paycheck calculator says $4,210 net. The direct deposit shows $4,063. Where did the $147 go? Almost always, it’s one of seven causes — and most of them are the calculator’s fault, not your employer’s.

First: rounding inside the federal withholding tables. The IRS publishes both wage-bracket tables and percentage-method tables in Publication 15-T. Payroll software like ADP, Paychex, Gusto, Workday, and Rippling each use slightly different rounding conventions and sometimes pick different methods for different gross-pay ranges. A paycheck calculator that uses the percentage method might be off by a few dollars compared to your employer’s wage-bracket table, or vice versa. The annual total is the same, but per-check there’s drift. The IRS allows both methods as long as the employer applies them consistently, so “off by $5” is usually the rounding gap, not an actual error.

Second: post-tax deductions the calculator never asked about. Things like Roth 401(k) contributions, after-tax life insurance over $50,000 of coverage (Section 79 imputed income), union dues, employee stock purchase plan (ESPP) contributions, charity matching gifts, deferred compensation contributions, and most importantly — wage garnishments. If you have a child support order, a federal tax levy, a defaulted student loan in collections, or a bankruptcy court order, the post-tax deduction is invisible to a generic paycheck calculator. We’ve seen people lose $400 a check to garnishments they assumed had ended. Federal law caps most garnishments at 25% of disposable earnings or 30 times the federal minimum wage, but child support can take up to 50–65% depending on circumstances.

Third: local income tax. NYC residents pay roughly 3.078% to 3.876% on top of NY State income tax, depending on income level. Yonkers residents pay an additional Yonkers tax. Philadelphia residents pay a wage tax around 3.75% (or 3.44% if non-resident). San Francisco, Newark, Detroit, Cleveland, Pittsburgh, Birmingham, Louisville, Cincinnati, Columbus, Kansas City — each has its own city or county income tax that a basic paycheck calculator often skips. The gap between gross and net is bigger in NYC than anywhere else in the country — a $200K salary nets about $124K after federal, state, city, and FICA, which most people learn the hard way during their first NYC paycheck. We get this question from clients moving to New York more than any other relocation. The expectation almost always overshoots reality by 8–12%.

Fourth: imputed income. If your employer pays for life insurance above $50,000 of coverage, the IRS treats the excess premium as taxable wages even though you never see the cash. Same with personal use of a company car, employer-paid gym memberships, certain domestic partner benefits, gross-up adjustments on relocation packages, and employer-paid tuition reimbursement above $5,250 per year. These add to your taxable wages without adding to your take-home, which means more withholding without more pay. A paycheck calculator that doesn’t ask about imputed income will overstate net pay. The pay stub will usually show a line called “imputed income” or “GTL” (group term life) buried below the regular wage lines — people miss it because it doesn’t add to net, only to gross.

Fifth: the calculator used the wrong filing status or W-4 setup. The 2020 W-4 redesign removed allowances entirely, but a lot of paycheck calculators still let you enter “exemptions” or “allowances” out of habit. If you input an old-style allowance count when your actual W-4 uses Step 2 multiple-jobs adjustments or Step 3 dependent credits, the numbers won’t match. The dependent credits on Step 3 reduce withholding by a fixed dollar amount per pay period — $2,200 per qualifying child under 17, divided by your number of pay periods. A bi-weekly worker with one child sees $84.62 less withheld per check. If the calculator and your actual W-4 disagree on this, the gap is exactly $84.62 multiplied by some number of dependents. Easy to spot once you know to look.

Sixth: a state-tax surprise. Pennsylvania has a flat 3.07% income tax with no standard deduction. New Jersey has nine brackets with the top one at 10.75% above $1 million. California adds a 1% mental health services surtax above $1 million. New York adds a 9.876% (highest) bracket and a separate NYC tax on top, which we already covered. Massachusetts charges an additional 4% “millionaire’s tax” on income over $1 million as of 2023. If a paycheck calculator uses a generic state engine that doesn’t account for state-specific quirks, the state line will be wrong. The state-level inaccuracies compound: most generic calculators are within 2% on the federal line and off by 8–15% on the state line for high earners in progressive-tax states.

Seventh: Social Security wage base and Additional Medicare timing. Social Security tax (6.2%) stops once year-to-date wages cross $184,500 in 2026. If you crossed that cap in October, your November and December checks are bigger than the calculator predicts because the calculator assumed the cap wasn’t hit yet. Conversely, Additional Medicare (0.9%) kicks in on wages above $200,000 from a single employer. A high-earner check in November might suddenly show MORE withholding than the calculator predicted because the 0.9% surcharge started withholding mid-year.

The fix is to compare line-by-line. Pull your pay stub, then run the calculator with the exact same gross, pre-tax deductions, filing status, and pay frequency. If the federal line matches and the FICA line matches but the state line is off, it’s a state-rule issue. If FICA is off by more than a dollar or two, it’s a wage-base or supplemental rate issue. If the gross matches but everything else is off by 8% or so, you’re probably missing a local tax. We’ve helped clients track these gaps down on calls more times than we can count. For New York City employees especially, the layered tax stack is easy to underestimate — federal, NY State, NYC city, NY SDI, NY PFL, plus federal FICA. That’s six lines minimum on every check.