Methodology

How tools are built

Calculators are written in TypeScript as pure functions inside a shared package (@bedrocka-tools/calc), with Vitest unit tests that cover edge cases: zero-basis Roth conversions, full pro-rata pro-rata scenarios where all IRA assets are pre-tax, IRMAA cliff edges where a $1 difference in MAGI moves a reader into the next surcharge tier, and every published sample problem we can find from primary sources. The package has no UI and no side effects — if a calculator gives the wrong answer, there is one file to fix and a failing test that tells us it was wrong.

Formula sourcing — primary sources only

We only cite primary sources. Blog-of-a-blog-of-a-PDF is not a source. The named experts whose published research defines the field also inform our methodology: Ed Slott (irahelp.com) on Roth mechanics and the five-year clock; Michael Kitces (kitces.com) on IRMAA-aware conversion sequencing and backdoor Roth pro-rata strategy; and Jeffrey Levine (Buckingham Wealth Partners / Kitces.com) on SECURE 2.0 RMD interaction with Roth conversion timing. Primary sources we use routinely on this site:

• IRS Publications — Pub 590-B (irs.gov/publications/p590b) — Distributions from Individual Retirement Arrangements; Form 8606 Instructions (irs.gov/forms-pubs/about-form-8606) — non-deductible IRA basis tracking; Pub 915 (Social Security benefit inclusion, relevant for IRMAA MAGI)
• Internal Revenue Code — IRC §408A (law.cornell.edu/uscode/text/26/408A) Roth IRAs; IRC §408(d)(2) (law.cornell.edu/uscode/text/26/408) IRA pro-rata / aggregation rule; IRC §86 taxation of Social Security benefits; IRC §401(a)(9) Required Minimum Distributions; IRC §72(t) early distribution penalty exceptions
• SSA and CMS IRMAA tables — Medicare Part B and Part D premium surcharge thresholds (medicare.gov/your-medicare-costs/part-b-costs); updated annually in the fall for the following calendar year
• OBBBA / TCJA extended brackets — Public Law 119-XX (One Big Beautiful Bill Act, signed July 4, 2025) permanently extending TCJA tax bracket rates; the scheduled 2026 cliff back to pre-2017 rates did not happen
• Treasury Regulations — Treas. Reg. §1.408A-1 through §1.408A-8 (Roth IRA qualification, conversion, and distribution rules); Treas. Reg. §1.401(a)(9)-1 through §1.401(a)(9)-9 (RMD rules)
• State Department of Revenue guidance — cited by state and labeled as state-specific when state conformity diverges from the federal IRC §408A rule (California, Pennsylvania, New Jersey noted)

Secondary sources are used only where a primary source does not exist and are always labeled as such.

Review process

1. Draft: calculator logic and explanatory copy are drafted, sometimes AI-assisted, always with the primary source pulled up in parallel and every non-trivial number checked against it.
2. SME review: each calculator is reviewed by a named human with operator experience in the domain — for Roth and IRA mechanics content, Byron Malone, and for new tools outside that expertise we engage domain reviewers (CPAs, Enrolled Agents) and credit them on the page.
3. Citation verification: every URL cited is spot-checked at publish time and every named rule or rate is re-checked against the source document.
4. Publish: with a Last updated stamp and a dateModified schema.org field on every page.

Update cadence

Every calculator is reviewed on a quarterly cadence. In addition, we update immediately on any of the following triggers:

• SSA publishes the annual IRMAA thresholds (typically November) for the following calendar year
• CMS announces Medicare Part B and Part D premium amounts
• IRS publishes updated Publication 590-B or Form 8606 instructions
• Congress passes legislation that changes Roth conversion rules, RMD ages, or the IRC §408A / §408(d)(2) interaction
• Treasury issues final or proposed regulations affecting Treas. Reg. §1.408A-1 through §1.408A-8
• IRS issues Revenue Procedures adjusting contribution limits or MAGI thresholds relevant to Roth eligibility

Error reporting

If a calculator gives you the wrong answer, we want to hear. Email info@bedrockatools.com with the tool, the inputs you used, and the output you got. We respond to every report within 3 business days; if the tool is wrong, we fix it and publish a correction note on our corrections page.

Per-category methodology

Each calculator category has a dedicated methodology page covering the primary sources, formula derivations, edge cases, and update protocol specific to that category. Calculators marked as launching soon are stubs in active development; the methodology pages are live so readers can evaluate the sourcing before the calculator ships.

• Roth Conversion — traditional-to-Roth conversion tax impact; multi-year ladder construction; bracket management under OBBBA-extended rates. Primary sources: IRC §408A, IRS Pub 590-B, OBBBA-extended bracket tables.
• Backdoor Roth — non-deductible IRA contribution + pro-rata conversion math; aggregation rule across all custodians; Form 8606 basis tracking. Primary sources: IRC §408(d)(2), Form 8606 instructions, Kitces analysis of pro-rata rule.
• IRMAA Planning — Medicare Part B and Part D premium surcharge lookback; MAGI calculation including Roth conversion income; appeal exceptions. Primary sources: IRC §86, SSA IRMAA tables, CMS Part B cost guidance.
• RMD Planning — Required Minimum Distribution calculation; RMD start age under SECURE 2.0; interaction with Roth conversion strategy before and after RMD age. Primary sources: IRC §401(a)(9), IRS Uniform Lifetime Table, Levine analysis of SECURE 2.0.
• Tax Bracket Strategy — filling the 12% and 22% brackets before RMDs push MAGI into higher territory; capital gains stacking interactions; Social Security benefit inclusion thresholds. Primary sources: OBBBA-extended brackets, IRC §86, IRS Rev. Procs. for annual inflation adjustments.

Limitations

Calculators on this site are estimatesfor educational use. They do not account for every state's conformity to IRC §408A, every individual income scenario (Social Security taxability cliffs, capital gains stacking), every plan-specific rule a custodian might apply, or the specifics of your individual filing situation including prior-year Form 8606 basis. They are not tax, financial, investment, or legal advice. Consult a licensed CPA, Enrolled Agent, or tax attorney for decisions with real dollars and real tax liability attached. The tools are designed to make you a better-informed buyer of professional advice, not a replacement for it.