Methodology

This page lists every rate, threshold and assumption the calculators on this site use, and — just as importantly — what they deliberately leave out. If a number on any page disagrees with this one, this page is the one to trust.

Tax year

All figures are for tax year 2026: the federal rates and thresholds in the IRS annual inflation adjustments, and each state's 2026 schedule.

Federal income tax

Taxable income is gross pay minus any pre-tax contributions you enter, minus the standard deduction for your filing status. Itemized deductions are not modelled.

The seven ordinary-income brackets are applied progressively, slice by slice. Single-filer thresholds (taxable income) are $12,400 for 12%, $50,400 for 22%, $105,700 for 24%, $201,775 for 32%, $256,225 for 35% and $640,600 for 37%. Married-filing-jointly thresholds are double the single figures up to the top bracket, which begins at $768,700. Head-of-household thresholds sit between the two.

Social Security and Medicare

• Social Security: 6.2% of wages up to the $184,500 wage base. Nothing above it.
• Medicare: 1.45% of all wages, with no cap.
• Additional Medicare: 0.9% on wages above $200,000. This is the employer withholding threshold, which applies per employee regardless of filing status — the figure reconciled on your return may differ.

Employer-side payroll taxes are not shown, because they do not come out of your pay.

Child tax credit

Applied at $2,200 per qualifying child, phasing out above $200,000 of income ($400,000 married filing jointly) at the statutory rate. No other credits are modelled.

State income tax

All 50 states plus the District of Columbia are covered, using each jurisdiction's own 2026 structure:

• Nine take no tax on wage income: Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, Wyoming.
• Fifteen apply a single flat rate.
• Twenty-seven use graduated brackets.

Where a state has its own standard deduction, it is applied before its brackets. Where a state offers personal exemptions or credits instead, those are generally not modelled, so the figure shown is a slight overstatement for those states. Local and municipal income taxes — New York City, most Ohio and Pennsylvania municipalities, Maryland counties — are never included.

Mortgage rates

Rates come from the Freddie Mac Primary Mortgage Market Survey, refreshed manually and stamped with the survey week on each page that uses them.

• 30-year and 15-year fixed rates are the surveyed PMMS figures.
• The 20-year fixed rate is an estimate; Freddie Mac does not survey that term.
• The 5/1 ARM rate is an estimate; Freddie Mac discontinued its ARM survey in 2022.
• The post-adjustment ARM rate is a default planning assumption, not a market rate.

Your actual quoted rate depends on credit score, loan-to-value ratio, points, property type and lender. Treat these as a starting point for comparison, not a quote.

Budget and affordability assumptions

The affordability calculator uses standard front-end and back-end debt-to-income guidelines and requires property tax, insurance and any HOA figures as inputs rather than guessing at them, because those vary far too much by county to estimate responsibly.

What is not modelled

• Itemized deductions, above-the-line adjustments and the QBI deduction
• Self-employment tax, 1099 income and quarterly estimated payments
• Equity compensation: RSUs, ISOs, ESPP
• Alternative minimum tax and the net investment income tax
• Multi-state income, part-year residency and reciprocity agreements
• Local and municipal income taxes
• Wage garnishments, union dues and post-tax benefit deductions

Corrections

Rates change and mistakes happen. If a figure here is wrong or out of date, the fix goes in immediately — every page carries the date its data was last refreshed.

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