2026 tax year · constants verified against primary sources

Financial calculators that show their working.

Every number on this site traces back to a Revenue Procedure, a CMS notice or a state fee schedule — and every table carries the date it was last checked. No sign-up, nothing stored, nothing sent anywhere.

Browse all calculators See the data sources

Calculators, all client-side

2026

Tax year constants

Versioned data tables

Cost, forever

Tax Calculators (2026)

View all →

SALT Deduction Calculator How much of your state and local tax payment survives the 30% phaseout. AMT Calculator Alternative Minimum Tax owed once your exemption starts eroding. Tips, Overtime, Car Loan & Senior Deductions Stack all four OBBBA deductions with their separate MAGI phaseouts. Quarterly Estimated Tax Calculator Self-employment tax, income tax and the safe harbor that avoids a penalty. Severance Pay Tax Calculator What actually lands in your account after supplemental withholding.

Mortgage Calculators (2026)

View all →

Mortgage Recast Calculator Three ways to use a lump sum, compared on payment, interest and payoff date. Biweekly Mortgage Calculator True biweekly versus the 13th-payment approximation, and what each saves. HELOC vs Cash-Out Refinance Keep a low first mortgage or replace it — compared on blended rate. Mortgage Points Calculator How long you must keep the loan for discount points to pay off. ARM vs Fixed Calculator Best and worst case adjustable-rate paths against a fixed comparison.

Retirement Calculators (2026)

View all →

Roth Catch-Up Calculator Whether your catch-up must be Roth in 2026, and the deduction that costs you. Roth Conversion Calculator Conversion room to the top of your bracket, with IRMAA and ACA warnings.

Health & Medicare Calculators (2026)

View all →

ACA Subsidy Calculator The 400% FPL cliff is back for 2026. See which side of it you are on. ACA MAGI Reduction Calculator Exactly how much to contribute pre-tax to get back under the cliff. IRMAA Calculator Your 2026 Part B and Part D premiums, set by your 2024 income.

Auto Loan Calculators (2026)

View all →

Negative Equity Car Loan Calculator What rolling an underwater balance into the next loan costs in interest.

Legal & Estate Calculators (2026)

View all →

Estate & Inheritance Tax by State Federal plus the 12 estate-tax states, 5 inheritance-tax states and their cliffs. LLC Cost by State Filing fee, annual report, publication rules and five-year total for all 50 states.

Money & Planning Calculators (2026)

View all →

Sabbatical Calculator How many months your savings buy once health cover and a re-entry buffer come out. Credit Card Points Calculator What your points are worth as cash, portal bookings or transfer partners.

Unit & Currency Converters

View all →

Currency, units, time zones and file sizes. In development.

Why the dates matter

Thirteen of the tables behind these calculators refresh on a fixed annual cycle: federal poverty guidelines in January, HSA limits in May, brackets and retirement limits in October and November, IRMAA in mid-November, and IRS interest rates every quarter. A calculator running last year's constants is worse than no calculator at all, so each one shows the date its data was last verified and flags itself when an update is overdue.