How we calculate & where our numbers come from

Methodology & Sources

Retire Projector exists to give you accurate numbers, so we are completely transparent about where every figure comes from and exactly how each calculator works. Our tax and contribution data is taken directly from official IRS publications, cited below, and reviewed each year.

Tax-year figures current for 2026 · last reviewed June 2026 · maintained by the Retire Projector editorial team.

Where our data comes from

The contribution limits, tax brackets and other rules used across the site are curated by hand, once a year, from primary IRS sources - never scraped or estimated:

Contribution & catch-up limits, the 415(c) total: the IRS annual cost-of-living notice (for 2026, IRS Notice 2025-67, released Nov 13, 2025) and the IRS pages Retirement topics – contributions and catch-up contributions.
IRA deductibility & Roth income (MAGI) phase-outs: the same notice plus IRS Publication 590-A.
Federal tax brackets & the standard deduction: the IRS annual inflation-adjustment Revenue Procedure for the tax year.
RMD life-expectancy factors: the Uniform Lifetime Table in IRS Publication 590-B (2022 revision).
Early-withdrawal rules & exceptions: Internal Revenue Code §72(t) and IRS Topic No. 558.

We store these as a small, versioned set of rule tables. The full 27-year history of contribution limits is published on our limit-history page.

How often we update

The IRS releases retirement-plan limits in the autumn (typically October–November) for the following year, and the tax-bracket Revenue Procedure around the same time. We update within days of each release and date every page. RMD tables and statutory early-withdrawal rules change rarely; we revisit them whenever the IRS revises them.

How each calculator works

Growth projections (401(k), IRA, millionaire)

We compound your balance year by year. Each year we add your contribution and any employer match, then apply your assumed annual return using a mid-year contribution convention (a common, slightly conservative approach). Contributions grow with your salary-growth assumption and are capped at the IRS 2026 limits. Where shown, the "today's dollars" figure discounts the result by your inflation assumption.

Tax calculations (paycheck, Roth comparison, conversion, early withdrawal)

We apply the current-year federal income-tax brackets for your filing status to taxable income after the standard deduction, and add FICA (Social Security + Medicare) where relevant. These are federal estimates - state and local taxes, credits, and phase-outs are not modeled, so your actual figures will differ.

RMDs

We divide your prior-year-end balance by the IRS Uniform Lifetime Table factor for your age - the most common case. A different table applies if your sole beneficiary is a spouse more than ten years younger.

State income tax (paycheck, conversion, early withdrawal)

When you select a state, we apply that state's 2025 income-tax brackets and standard deduction (for your filing status) on top of the federal calculation. State data is curated from each state's Department of Revenue. What we model: the nine no-income-tax states (0%), the flat-rate states, and graduated brackets for the rest, with married-filing-jointly thresholds resolved per state. What we do NOT model in this version: local/city income taxes (e.g. New York City, Maryland counties, Ohio municipalities), state-specific exclusions that exempt some or all 401(k)/IRA/pension income (common for retirees - e.g. Illinois, Pennsylvania, Mississippi, Iowa), credits, and the latest mid-year rate changes. Because state figures lag the federal release, they reflect the 2025 tax year. Treat state results as a solid estimate and confirm with your state's Department of Revenue.

Assumptions, not guarantees

Investment return, inflation and salary growth are assumptions you control, not forecasts. Markets are volatile and past performance does not predict future results. Default values are provided only for convenience and are not a recommendation. Every projection is an estimate to help you understand your options - it is not a promise of future results.

Not financial advice

Retire Projector is an independent educational tool and is not affiliated with the IRS or any government agency. Nothing here is personalized financial, tax or investment advice. Always confirm current figures at IRS.gov and consult a qualified professional before making decisions. Found a figure that looks wrong? Tell us - accuracy is the whole point of this site.