Uniform Lifetime Table

Published in Appendix B of IRS Publication 590-B as Table III, the Uniform Lifetime Table applies to unmarried account owners, married owners whose spouses are not more than 10 years younger, and married owners whose spouses are not the sole beneficiary, which together covers the large majority of RMD calculations. The one exception that matters: a sole-beneficiary spouse more than 10 years younger uses the Joint Life Table (Table II), which produces larger divisors and smaller required withdrawals.

Reading the table is a single division. A 73-year-old with $500,000 in tax-deferred accounts divides by 26.5, an RMD of about $18,868. Because the factor shrinks every year while the balance may not, the required share of your money climbs from roughly 3.8 percent at 73 to 8.2 percent at 90. The RMD calculator does the lookup and division for your age and balance.