Payroll Guide 2026: How Your Paycheck Is Calculated
You work all month, and then the deposit that lands in your bank account is mysteriously 25%–30% smaller than your salary. The gap between gross pay and net pay is not one deduction but a stack of them: federal income tax withholding, FICA payroll taxes, optional pre-tax benefits, and state income tax. Each layer has its own rules, caps and quirks — and some of them, like the Social Security wage base, change every year. This guide walks through a 2026 US paycheck line by line: what each deduction is, how it is calculated, where the 2026 thresholds sit, and which levers (401(k), health premiums, W-4 elections) you actually control. By the end you will be able to read your payslip like a payroll processor does.
1. Anatomy of a paycheck
Every US payslip, whether paper or digital, follows the same skeleton. The order matters: pre-tax deductions come off first and shrink the base used for federal tax, while FICA and post-tax items apply to their own bases.
| Line | What it is | 2026 typical size | Calculated on |
|---|---|---|---|
| Gross pay | Salary or hours × rate, plus bonuses | 100% — your starting point | — |
| Pre-tax 401(k) | Traditional pre-tax retirement deferral | 5%–10% of gross (2026 deferral limit $24,500) | Gross pay |
| Pre-tax health premium | Your share of medical/dental insurance | $1,500–$6,000/year | Gross pay |
| Federal income tax | Progressive withholding per your W-4 | 10%–37% marginal | Gross − pre-tax items − standard deduction |
| Social Security | FICA component 1 | 6.2% up to $176,100 of wages | Gross pay (pre-tax deductions do not reduce it) |
| Medicare | FICA component 2 (+0.9% surtax) | 1.45% all wages; +0.9% above $200k/$250k | All wages, no cap |
| State/local tax | State income withholding | 0%–13% depending on state | State rules; often similar to federal taxable |
| Post-tax deductions | Roth 401(k), garnishments, union dues | Varies | Net of everything above |
| Net pay | What actually reaches your account | ~70%–78% of gross for mid-range salaries | — |
2. Federal income tax withholding
Federal withholding is an estimate of your annual tax, taken gradually so you "pay as you go". The math your payroll system performs is close to this:
- Start with gross wages for the year and subtract pre-tax deductions (traditional 401(k), health premiums, FSA/HSA).
- Subtract the standard deduction — for 2026, a projected $16,100 for Single filers and $32,200 for Married Filing Jointly (itemize instead only if your deductible expenses exceed these).
- Apply the 2026 progressive brackets to what remains: 10% on the first $12,400 (Single), 12% up to $50,400, 22% up to $105,700, 24% up to $201,775, 32% up to $256,225, 35% up to $640,600, and 37% above (thresholds double for MFJ).
Only your marginal rate — the rate on your last dollar — is high. Your effective federal rate is much lower because earlier dollars are taxed at 10% and 12%. A $75,000 Single earner with 5% pre-tax 401(k) and $3,000 health premiums owes roughly $7,700 in federal tax, an effective rate near 10.8%, even though their marginal bracket is 22%.
What you control here is the W-4. The 2020+ redesign removed allowances; now you set a dollar amount of other income, deductions and extra withholding per pay period. Claim dependents in Step 3 and less is withheld; leave Step 4(c) blank and the default tables apply. Withhold too little and you owe an underpayment penalty plus a surprise bill in April; withhold too much and you've given the IRS an interest-free loan until your refund arrives.
3. FICA: Social Security and Medicare, line by line
FICA (the Federal Insurance Contributions Act) funds Social Security and Medicare. Unlike income tax it is a flat payroll tax with caps and surcharges, and your employer pays a matching share you never see.
- Social Security — 6.2% up to the wage base. In 2026 the taxable wage base is $176,100, so the maximum employee contribution is $10,918.20. Every dollar above that is Social-Security-free for the rest of the year — high earners see a visible paycheck jump in the final months. Your future benefit is computed on these covered wages, which is why the cap exists.
- Medicare — 1.45% on all wages, no cap. There is no wage base for Medicare; the 1.45% applies from your first dollar to your last.
- Additional Medicare Tax — 0.9% surcharge. Once wages exceed $200,000 (Single) or $250,000 (MFJ), an extra 0.9% applies to the excess — but note the employer only triggers withholding at $200,000 regardless of filing status, so joint filers often need to plan for it via estimated payments or extra W-4 withholding.
- Employer match. Your employer pays another 6.2% + 1.45% on the same bases. Economists debate who really bears it, but on paper your employer's FICA cost is roughly 7.65% on top of your gross.
Self-employed people pay both halves under SECA — 12.4% Social Security and 2.9% Medicare — but may deduct the employer-equivalent portion. If you freelance on the side, remember your side income stacks on top of wages for the Additional Medicare threshold even if your main job already withheld.
4. Pre-tax vs post-tax deductions
Not all deductions are equal — the difference is when the money escapes taxation.
✅ Pre-tax deductions (taken before income tax)
- Traditional 401(k): avoid income tax today, pay ordinary rates in retirement
- Health/dental premiums via a Section 125 plan: lower federal (and usually state) tax
- FSA/HSA contributions: pre-tax dollars for healthcare; HSAs are triple tax-advantaged
- Effect: lowers federal taxable wages, but not Social Security wages (401(k) still bears 6.2% FICA)
⚠️ Post-tax deductions (taken after all taxes)
- Roth 401(k): pay tax now, withdraw tax-free later — better if you expect higher future rates
- Garnishments, child support, union dues: no tax effect at all
- Disability/life insurance paid post-tax: benefits later arrive tax-free
- Effect: zero impact on current taxable wages — pure cash-flow out
A useful rule of thumb: if you are in the 22% bracket or higher and more than ~10 years from retirement, traditional (pre-tax) 401(k) contributions usually win; if you are early-career in the 12% bracket, Roth contributions lock in today's low rate. Health premiums are almost always best paid pre-tax through a Section 125 cafeteria plan.
5. Bi-weekly vs semi-monthly: the frequency trap
Two pay frequencies sound identical and are not:
| Frequency | Paychecks/year | Per-paycheck gross on $75,000 | Notes |
|---|---|---|---|
| Weekly | 52 | $1,442.31 | 3–4 paychecks most months; two "5-week" months per year |
| Bi-weekly | 26 | $2,884.62 | Same amount every two weeks; 2 months a year contain 3 paychecks |
| Semi-monthly | 24 | $3,125.00 | E.g. 15th & last day; each paycheck is slightly larger; coincides with rent |
| Monthly | 12 | $6,250.00 | Rare in the US outside government and academia |
Annual totals are identical — $75,000 is $75,000 — but the cash-flow rhythm differs. With bi-weekly pay, each check covers 14 days and the per-check amount is smaller; two months per year contain three checks, which savvy budgeters redirect straight into savings or a 401(k) top-up before lifestyle creep absorbs them. With semi-monthly pay, checks align with monthly bills and are larger, but there is no bonus "extra check" month. Withholding tables annualize either way, so your total yearly tax is the same — only timing shifts.
6. State and local income tax: the missing layer
Federal numbers are only part of the story. Nine states (as of 2026: Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, Wyoming) levy no wage income tax; New Hampshire taxes only interest and dividends. At the other end, California tops out at 12.3% (plus a 1% mental-health surtax over $1M), Hawaii reaches 11%, and New York City adds a city layer of roughly 3%–4%. Most states use brackets loosely modeled on the federal system with their own standard deductions or credits; a handful (Pennsylvania at a flat 3.07%, Illinois at 4.95%) use a single flat rate. Local taxes add more in cities like Philadelphia, Denver and Columbus.
Practically: a $75,000 salary nets about $3,000–$4,000 more per year in a no-tax state than in California — enough to matter in a relocation decision, though cost of living usually dominates. Because state rules vary too much to model here, the payroll calculator on this site deliberately shows federal + FICA only; check your state's revenue department for exact withholding tables.
👉 Use the 2026 Payroll & Take-Home Pay Calculator
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7. Quick answers to frequent paycheck questions
- Why did my paycheck change mid-year? You likely hit the $176,100 Social Security wage base (paycheck jumps) or crossed the Additional Medicare threshold (paycheck drops 0.9% on the excess).
- Is FICA refundable? No — it is not an income tax and never comes back as a refund, though excess Social Security withheld by two employers in one year can be claimed as a credit on your 1040.
- Does a raise always increase take-home proportionally? Not exactly: the portion that crosses into a higher bracket is taxed at the marginal rate, and crossing $176,100 pauses Social Security tax, which can make a raise feel bigger than expected.
- Why is my bonus taxed so heavily? Bonuses use flat supplemental withholding (22% federal under $1M), which feels like a penalty but is trued up on your annual return.