How TheFinSense Calculates
📅 Last Updated:
Every dollar figure on TheFinSense traces back to a specific formula, a specific data source, and a specific date. This page documents the calculation methodology behind our analysis so you can verify, challenge, or extend any number we publish.
Core Formulas
Lump Sum Future Value
Used when a single deposit grows without additional contributions.
Lump Sum + Monthly Contributions (Annuity)
Used when regular deposits supplement an initial balance.
Gap Calculation
Every “gap” figure is the difference between two FV calculations using the same time horizon and contribution schedule, with only the cost variable changed.
Data Sources
We use primary sources only. No secondhand citations.
| Data Type | Source | Update Frequency |
|---|---|---|
| T-Bill Rates | FRED (Federal Reserve Economic Data) — DGS3MO series | Weekly |
| HYSA Rates | DepositAccounts.com + FDIC National Rate | Per article |
| Brokerage Sweep Rates | Direct from broker websites (Schwab, Fidelity, Vanguard) | Per article |
| Expense Ratios | Morningstar fund pages | Per article |
| Tax Brackets | IRS Revenue Procedures (irs.gov/pub/irs-drop/) | Annually |
| Regulatory Filings | FINRA Rule Browser, SEC EDGAR, Federal Register | Per article |
| Academic Research | NBER, SSRN, direct journal PDFs | Per article |
| Market Returns | S&P 500 historical data via FRED or Damodaran (NYU Stern) | Per article |
Standard Assumptions
Unless stated otherwise in the article, these defaults apply:
| Variable | Default | Why |
|---|---|---|
| Gross return rate | 10% nominal | S&P 500 long-term average (1926-2024) |
| Inflation rate | 3% | Fed long-run target + historical average |
| Time horizon | 30 years | Working career standard |
| Tax filing status | Married Filing Jointly | Most common US filing status |
| State tax | 0% (unless specified) | Conservative — state tax makes gaps larger |
| Rounding | Dollar amounts to nearest whole dollar | Readability |
| Percentages | 2 decimal places | Precision without clutter |
Sensitivity Analysis
Every article includes a sensitivity section showing how the gap changes when assumptions shift. We vary at least 2 independent variables (typically return rate and cost rate) across 3 levels each.
When a third variable creates interaction effects (e.g., tax bracket + contribution level + return rate), we present interaction tables showing the full matrix.
What We Do Not Account For
Every methodology has boundaries. Ours does not account for:
| Factor | Why Excluded | Impact Direction |
|---|---|---|
| Behavioral deviation | We assume the investor follows the plan — most do not | Gaps are likely larger in practice |
| Tax law changes | We use current law as published — future legislation is unpredictable | Could increase or decrease gaps |
| Sequence of returns risk | We use flat annual rates — real markets fluctuate | Historical backtest sections address this |
| Advisory fees beyond scope | Each article isolates one cost — interactions are noted but not compounded | Total cost is higher than any single article shows |
How to Verify Our Numbers
Every article provides enough information for you to replicate the calculation:
- Find the Calculation Transparency section (typically in H2_3 or H2_4).
- Note the formula, input values, and stated result.
- Open any FV calculator (or a spreadsheet) and input the same values.
- If your result differs by more than $1 from ours, contact us — we will correct it publicly.
Per-Article Calculation Record
Revenue Growth Accrual Quality — $109,616
Article: Revenue Growth Quality: The 18% Accrual Trap (2026) · Published April 13, 2026
Correction Policy
When we find or are notified of an error, we:
- Correct the article within 48 hours.
- Update the “Last Updated” date.
- Add an entry to the article’s Correction Log with the date, what changed, and why.
- Do not delete the original claim — we show what was wrong and what replaced it.
Transparency is not optional. If we published it, we own it.
This page is reviewed quarterly. Questions about our methodology: [email protected]
Educational quantitative analysis based on published data. Not investment, tax, or legal advice. Consult a licensed professional before acting on any calculation. About TheFinSense.
