Taxes and data sources
How tax is counted, and where the figures come from.
Tax follows the type of bond
Interest on US bonds is taxed at a US federal rate worked out from the 2026 tax brackets, single for one person and married filing jointly for two or more, plus the 3.8% investment income tax. The rate depends on how much interest your spending produces. Interest on a country's own bonds is taxed at that country's rate, which is zero where there is no tax on this income. Both the interest and the yearly inflation adjustment on the principal are taxed each year. US state tax is not included.
Plan lengths
The workbook behind the site covers plans of 20, 25 and 30 years. For 35 years, 40 years and the rest of your life, we extend the tax estimate with the same model (the effect is up to 1.5% for 35 and 40 years and up to 4% for the rest of your life). Local tax rates are first estimates for most countries and have not all been checked one by one. Other income on Will the money last? is taxed at 30% unless you change the rate.
Sources
- World Bank Poverty and Inequality Platform, for household spending and income by country.
- World Inequality Database, for tax-record income at the top of the range.
- National statistics offices and central banks.
- The US Bureau of Labor Statistics consumer price index (the 12-month change to August 2026, 3.4%), for US inflation, and the International Monetary Fund's World Economic Outlook, for other countries' inflation.
- open.er-api.com, for exchange rates.
- US Treasury and the Federal Reserve Bank of St. Louis (FRED), for bond yields.
- Internal Revenue Service 2026 tax tables.
- Numbeo and other cost-of-living sources and published retiree guides, for places with no household survey.
- For how long you might live: World Health Organization life tables (see How long you might live).
- For history: Aswath Damodaran (stock returns, dividends and US prices, 1928 to 2025).
A company's own claim, for example a transfer service's registration, is used only where the text says it is the company's claim. Photographers and sources are on Photo credits.
Where the method changes
Whenever we change the way something is done, we add a dated note on How it works, under "What changed and when".