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Source register

Sources and updates

We prefer primary, official material and keep time-sensitive assumptions separate from general formulas.

Last updated: September 5, 2026

Primary sources

Internal Revenue Service (opens in a new tab)

Retirement contribution limits, distributions, tax basis and federal tax topics

Social Security Administration (opens in a new tab)

Retirement ages, claiming information and personal benefit estimates

Consumer Financial Protection Bureau (opens in a new tab)

Mortgage, auto lending, debt, budgeting and emergency-fund guidance

SEC Investor.gov (opens in a new tab)

Investing basics, fees, compound growth and 529 plan education

Bureau of Labor Statistics (opens in a new tab)

Historical CPI-U data and inflation context

Department of Labor (opens in a new tab)

Workplace retirement plan information and fee education

ADA.gov and W3C (opens in a new tab)

Web accessibility guidance and WCAG 2.2

Update cadence

  • Retirement contribution limits are reviewed after the annual IRS announcement and before a new tax year.
  • Social Security ages and claiming guidance are reviewed annually and after a material statutory change.
  • CPI history is reviewed after BLS updates and before adding a newly completed year.
  • Mortgage, auto and consumer disclosures are reviewed at least quarterly.
  • State and local rules are reviewed before activation and carry an explicit effective and expiration date.
  • External links are checked automatically, with a manual source review at least quarterly.

Expiration behavior

When a dated rule expires, we stop using it until it has been reviewed. The calculator will ask you to enter the value or mark the result as incomplete instead of quietly reusing last year's number.

Using a source responsibly

A linked source may describe eligibility, exceptions or definitions that a calculator cannot fully model. Read the current official material and the documents for your own account, loan or plan. A link does not mean the agency endorses this site.