Do My NumbersMethodology

How the IRS tables and RMD tool works

Unlike the other calculators, the IRS life expectancy tables and RMD tool models nothing. It looks a number up in a table the IRS prints and divides by it. The work is in choosing the right table, and in reading it exactly as published.

Choosing the table and dividing

The tool asks whether you are the owner or a beneficiary, and for an owner whether the spouse is the sole beneficiary and how much younger.

  • An owner whose spouse is the sole beneficiary and more than 10 years younger reads Table II at both ages.
  • Every other owner reads Table III, the Uniform Lifetime table.
  • A beneficiary using life expectancy reads Table I at their age in the first distribution year, then takes one off for each later year.
Δ=x−y\Delta = x - y
Age gap Δ: How many years younger your spouse is than you, using both ages on your birthdays this year.
L=Table III value at age xL = \text{Table III value at age } x
Distribution period: The IRS life expectancy factor for your age. The required minimum distribution is the balance divided by it.
L=Table II value at ages x and yL = \text{Table II value at ages } x \text{ and } y
L0=Table I value at age xL_{0} = \text{Table I value at age } x
Starting distribution period L₀: The Table I life expectancy at the beneficiary’s age in the year distributions begin.
L=L0−jL = L_{0} - j
Distribution period: The IRS life expectancy factor for your age. The required minimum distribution is the balance divided by it.
RMD=Balance on Dec 31 last yearDistribution period\text{RMD} = \frac{\text{Balance on Dec 31 last year}}{\text{Distribution period}}
Required minimum distribution: The smallest amount the IRS requires you to take out of a tax-deferred retirement account for the year.

The tables are stored exactly as printed. The last printed age (“120 and over” in Table III) is stored as one row that covers every older age, the same way the publication uses it. The balance is the amount on December 31 of the year before; the tool takes the figure you enter as that balance.

Starting values

  • An owner of 75 with $500,000, spouse 72 and sole beneficiary. The gap of 3 years is not more than 10, so the example uses Table III, the table most owners use.
  • First year of distributions for a beneficiary. The later-years count starts at zero until changed.

The publication it reads

  • IRS Publication 590-B (2025) life expectancy tables, Internal Revenue Service, US Department of the Treasury. Edition: Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs). For use in preparing 2025 Returns. Retrieved October 22, 2026.

Each file keeps its source address, edition and retrieval date, and is tested against figures the publisher prints. All of them are listed on the data sources page.

The tool’s tests read factors for samples of ages straight from the saved IRS page, and reproduce four of the publication’s own worked examples.

Rules the tool doesn’t apply

  • The 5-year and 10-year rules, and the special choices of a surviving spouse.
  • Trusts, estates and several beneficiaries.
  • The year of the owner’s death and owners who died after their required beginning date.
  • Roth IRAs and workplace plans, where some rules differ, and the excise tax on a missed RMD.