How we calculate
Last updated 10 September 2026
Every figure below is checkable. If you find one that disagrees with the official source, it is a bug and we want to know.
Federal income tax, 2026
Taxable income is gross pay, less pre-tax deductions, less the standard deduction. The brackets are marginal: each rate applies only to the slice of income that falls inside it.
| Rate | Single filer taxable income |
|---|---|
| 10% | $0 to $12,400 |
| 12% | $12,400 to $50,400 |
| 22% | $50,400 to $105,700 |
| 24% | $105,700 to $201,775 |
| 32% | $201,775 to $256,225 |
| 35% | $256,225 to $640,600 |
| 37% | $640,600 and above |
Standard deduction: $16,100 single, $32,200 married filing jointly, $24,150 head of household.
Source: Internal Revenue Service annual inflation adjustments.
Social Security and Medicare
| Tax | Rate | Applies to |
|---|---|---|
| Social Security | 6.2% | Wages up to $184,500 |
| Medicare | 1.45% | All wages, no cap |
| Additional Medicare | 0.9% | Wages above $200,000 (single) |
These are the employee shares. Your employer pays a matching amount for Social Security and Medicare, which does not appear on your pay stub.
Source: Social Security Administration contribution and benefit base.
The order deductions are applied
This order determines the result, so it is worth stating explicitly:
- Section 125 deductions (health, dental, vision, FSA, payroll HSA) come off first and reduce both income tax and FICA wages
- Traditional 401(k) and 403(b) contributions come off next and reduce income tax wages only
- FICA is charged on the wages remaining after step 1
- The standard deduction is subtracted, and federal brackets applied to what is left
- State tax is calculated on the state's own definition of taxable income
State income tax
States are modelled one of three ways: no tax on wages, a single flat rate, or a progressive bracket schedule with its own standard deduction. Each state page links to the revenue department the figures came from.
We publish a state page only once its figures have been checked against that source for the current tax year. States still under review do not get a page, which is why the state list is shorter than fifty.
Loan amortisation
The scheduled monthly payment uses the standard amortising formula:
P × r × (1 + r)^n ÷ ((1 + r)^n − 1)
where P is the principal, r the monthly rate (annual rate
divided by twelve) and n the number of months. The schedule is then
simulated month by month: interest is charged on the outstanding balance, the
remainder of the payment reduces principal, and the final payment is trimmed to
whatever is actually left owing.
Compound interest
Simulated monthly rather than solved with the closed-form future-value equation. That formula assumes contributions arrive at the same frequency as compounding, which is rarely true — people contribute monthly to accounts that compound daily or quarterly. Contributions are added at the start of each month, then growth for that month is applied.
Overtime
Follows the FLSA regular-rate method. Total straight-time earnings, including non-discretionary bonuses, are divided by hours actually worked to give the regular rate. Overtime hours are then paid at 1.5 times that rate, and double-time hours at 2 times, rather than at the base hourly wage.