This site covers the forms and numbers that determine how much of your income is sheltered, deferred, or exempt from federal tax. Each page gives you the rule, the threshold, a real example, and a direct link to the calculator that applies it.
All figures reflect 2026 IRS limits. Where 2026 has not yet been released, the most recent published figures are shown with a clear notation.
Browse by Form or Topic
W-4 Withholding & Exemptions
When you can claim exempt, allowances, and extra withholding rules.
W-2 Box 12 Codes
Every Box 12 code explained with dollar limits and withholding impact.
1099-NEC vs W-2
Reporting thresholds, tax treatment, and worker classification rules.
Education Credits
American Opportunity and Lifetime Learning credit limits and AGI phase-outs.
Saver's Credit
AGI thresholds and credit rates for retirement savers at lower incomes.
HSA Contribution Limits
2026 self-only and family HSA limits, HDHP minimums, and catch-up rules.
FSA Contribution Limits
Healthcare and dependent care FSA limits, carryover rules, and grace periods.
Retirement Contribution Limits
2026 401(k), IRA, Roth IRA, and SIMPLE IRA limits with catch-up thresholds.
Itemized Deduction Limits
SALT cap, mortgage interest limits, charitable deduction rules, and medical thresholds.
Ready to Calculate?
Use our free tax calculators to apply these rules to your actual numbers.