Josh

Financial modeling and data

Numbers don't argue, but the assumptions behind them do - and they should be visible.

Josh covers the data-heavy side of PennyCalc - the pages where the math has to be exactly right and the assumptions have to be visible. His background is in financial modeling at a private equity firm, the kind of work where a misread amortization schedule has real consequences, and that habit shows up in how these tools are built: full breakdowns, stated assumptions, and no black boxes.

He writes and maintains the mortgage, tax bracket, retirement, compound interest, and capital gains tools, plus the long-form history pages that put today's rates and brackets in decades of context. His rule for any page that argues a number is that the reader should be able to see every step that produced it.

The reason most online financial calculators undercount the answer by 30-40% is that the assumption that produced the gap is hidden in a default value the reader never sees. Josh built the alternative because every PE diligence model he ever ran taught him the same lesson: the number is only as good as the assumption you can defend. The PennyCalc tools that bear his name are the ones where every input is editable, every default is sourced, and every projection includes the case where the assumption is wrong.

pages authored or co-authored

topic areas covered

IRS Pub 17 · FRED · JCT · SSA Trustees

primary sources

Quarterly

re-verification cycle

What Josh covers

Mortgage calculationsFederal income taxRetirement modelingCompound interestCapital gainsHistorical rate datasets

My editorial standards

Every assumption is editable. Every default value on a Josh-owned calculator can be overridden. If the user disagrees with our property tax estimate for their county, the input is right there.
No black-box math. Every output is decomposed into its inputs. A "$2,935 monthly payment" breaks down into the P&I, escrow, and PMI line items so the reader can audit each piece.
Source the default, not just the number. Property tax defaults cite the state median per the Tax Foundation. Mortgage rate defaults cite the Freddie Mac PMMS week. Inflation defaults cite the BLS series ID. If a default lacks a source, it doesn't ship.
The history page must include the table, not just the chart. Charts are for shape, tables are for citation. Every history page Josh owns has both.
The amortization schedule is mandatory. Mortgage and loan tools that hide the schedule are useful for sales conversion and useless for actually planning the next 30 years.

How I verify a fact before it ships

Tax-related figures: cross-checked against the most recent IRS publication for that figure (Pub 17 for tax brackets, Pub 590 for IRA limits, Pub 502 for medical/HSA, and so on) plus the Tax Foundation historical archive for series longer than 10 years.
Historical rate series: pulled from Federal Reserve Economic Data (FRED) by series ID, never from a secondary source. Series IDs are listed in the methodology.
Retirement contribution limits: IRS Notice for the current year, then cross-checked against published Joint Committee on Taxation explanatory documents for any rule changes.
Social Security data: SSA Trustees Reports primary, with the COLA announcement page as the formal annual marker.

Signature work

U.S. Federal Tax Brackets History (1913-2026)

The most-cited PennyCalc page in Microsoft Copilot grounding queries, by a wide margin. It exists because no single source combined the rate series, the legislative history, and the year-by-year context in a citable format.

Mortgage Calculator with PMI, Taxes & Insurance

The calculator that proves the thesis that most online mortgage tools undercount the monthly payment by 30-40%. Implements the actual Homeowners Protection Act 78% LTV PMI auto-cancellation rule, not the 80% lenders prefer to quote.

Capital Gains Tax Rate History (1922-2026)

The long-term rate series alongside the legislative events that moved it. Built for the tax-planning audience that needs to ground a "what was this rate in 19XX" question precisely.

IRA Contribution Limit History (1974-2026)

Every year from EGTRRA-era catch-up changes to the SECURE 2.0 super-catch-up. Pairs with the retirement projection calculator.

Working with the team

Josh works most closely with Michael on the calculator implementations - Josh builds the spreadsheet that proves the math, then Michael ports it into the Astro components with the right rounding, edge cases, and regression coverage. On the editorial side, Josh hands the long-form history pages to Jessie for a final pass on whether the explanation will land for a reader who isn't already comfortable with the numbers. The byline says one name; the work usually has all three fingerprints.

What I'm working on now

Currently extending the history-page series with the underserved data sets: estate tax exemption history (especially relevant given the 2026 TCJA sunset), federal funds rate history with a Fed chair tenure overlay, and the long-form Backdoor Roth methodology that hasn't been written carefully anywhere else.

Spotted an error?

Math mistakes get fixed within 24 hours, sourcing questions get addressed in the methodology, and missed nuances get acknowledged in a footnote. The fastest path: [email protected], subject line "Josh / [page URL]". You'll get a reply, not a form.

PennyCalc is a team of data people who build the financial tools they use themselves. Read more about how we work on the about page and how we source every figure in our methodology.