Regulatory & Government Sources
United States
- CFPB Regulation Z (12 CFR 1026) — Truth in Lending Act implementation; APR calculations, Loan Estimate format
- CFPB "Ability-to-Repay" Rule (12 CFR 1026.43) — Qualified mortgage standards, 43% DTI threshold
- Fannie Mae Single Family Selling Guide — Underwriting guidelines, LTV limits, PMI requirements
- Freddie Mac Single-Family Seller/Servicer Guide — Conforming loan standards
- IRS Publication 936 — Home mortgage interest deduction
- IRS Publication 590-A/B — IRA contribution limits, distribution rules
- IRS Publication 527 — Residential rental property (depreciation context)
- Department of Labor ERISA — 401(k) contribution limits, RMD rules
- Social Security Administration — Benefit calculators, full retirement age tables
United Kingdom
- FCA MCOB (Mortgages and Home Finance: Conduct of Business) — Affordability assessment, APRC calculation
- FCA CONC (Consumer Credit) — Creditworthiness assessment, APR calculation
- HMRC Savings and Investment Manual (SAIM) — ISA limits, tax treatment
- HMRC Pensions Tax Manual (PTM) — Annual allowance, lifetime allowance, carry forward
- MoneyHelper (formerly Money Advice Service) — Consumer-facing guidance, budget planner methodology
- Bank of England — Base rate history, mortgage market statistics
- UK Government Gateway — Tax calculators, National Insurance rates
Australia
- ASIC Regulatory Guide 203 — Mortgage responsible lending obligations
- ASIC Regulatory Guide 175 — Credit licensees' obligations
- APRA Prudential Standards (APS 220, APS 113) — Capital adequacy, credit risk
- ATO (Australian Taxation Office) — Superannuation caps, contribution rules, co-contribution
- Moneysmart (ASIC) — Budget planner, compound interest, retirement calculators methodology
- RBA (Reserve Bank of Australia) — Cash rate, lending rate statistics
- FASEA (Financial Adviser Standards) — Best interest obligations (context)
Academic & Industry Texts
- Bodie, Kane, Marcus — "Investments" (12th ed.) — Ch. 5 (Risk/Return), Ch. 6 (Portfolio Theory), Ch. 14 (Performance Evaluation)
- Fabozzi — "Fixed Income Mathematics" (4th ed.) — Bond math, mortgage-backed securities, amortization
- Hull — "Options, Futures, and Other Derivatives" (10th ed.) — Ch. 14 (Monte Carlo Simulation)
- Kitces — "Monte Carlo Analysis for Financial Planning" (Kitces Report) — Best practices for financial planning simulations
- Pfau — "Retirement Planning Guidebook" — Safe withdrawal rates, sequence risk
- Vanguard — "Capital Markets Model" Methodology Papers — Return assumptions, correlation matrices
- Morningstar — "Asset Allocation Research" — Portfolio construction frameworks
Calculator-Specific Sources
Mortgage Payment / Amortization / Overpayment
- Standard amortization formula (present value of annuity)
- CFPB Loan Estimate Explorer (sample calculations)
- Fannie Mae Desktop Underwriter documentation (PMI factors)
Compound Interest
- Future value of annuity due/ordinary formulas
- EAR/APR conversion (Reg Z Appendix J)
Mortgage Affordability
- CFPB Ability-to-Repay / Qualified Mortgage rule
- Fannie Mae Form 1003 (Uniform Residential Loan Application) — DTI calculation
- UK FCA MCOB 11.6 (Affordability Assessment)
Savings Goal
- Payment formula rearranged for PMT
- MoneyHelper "Savings Calculator" methodology
Debt Payoff Planner
- Avalanche: Standard debt optimization (highest rate first minimizes interest)
- Snowball: Behavioral finance literature (Gal & McShane, 2012; Motivation & progress)
Retirement Savings
- Bengen (1994) "Determining Withdrawal Rates" — 4% rule origin
- Trinity Study (Cooley, Hubbard, Walz, 1998) — Portfolio success rates
- Pfau (2010+) — Updated safe withdrawal rates with modern valuations
- Social Security Administration Actuarial Life Tables
Net Worth
- Standard balance sheet methodology (GAAP/IFRS framework for individuals)
- Federal Reserve Survey of Consumer Finances (category definitions)
Budget Calculator
- 50/30/20 rule: Warren & Tyagi "All Your Worth" (2005)
- MoneyHelper Budget Planner category framework
- CFPB Financial Well-Being Scale (category relevance)
Wealth Simulator (Monte Carlo)
- Hull Ch. 14 — Geometric Brownian Motion for asset prices
- Kitces Report — Practical implementation for financial planners
- Vanguard VCMM — Return distribution assumptions
Data Sources (Default Rates & Assumptions)
Default values in calculators are illustrative averages as of January 2025. Sources for defaults:
- Mortgage Rates: Freddie Mac PMMS (US), Bank of England quoted rates (UK), RBA indicator lending rates (AU)
- Investment Returns: Vanguard 10-year nominal return projections (60/40 portfolio ~7%)
- Inflation: Central bank targets (2% US/UK, 2-3% AU)
- Property Tax: US national average ~1.2%; UK Council Tax bands; AU council rates
- Insurance: US average ~0.35% home value; UK buildings insurance; AU home insurance
- PMI: US: 0.5–1% loan amount; UK: not applicable (LTV > 90% requires different product); AU: LMI 0.5–2%
Active Affiliate Partners (Q1 2025)
Per our Affiliate Disclosure, current partners include:
- Mortgage marketplaces: LendingTree, Bankrate, NerdWallet (via impact.com/CJ)
- Brokerages: Vanguard, Fidelity, Schwab, Interactive Brokers (direct/impact.com)
- Tax software: TurboTax, TaxAct, FreeTaxUSA
- Budgeting: YNAB, Monarch Money
- Insurance: Policygenius, Lemonade
Updated quarterly. See Affiliate Disclosure for commission details.
Verification & Updates
- Regulatory sources checked monthly for updates
- Rate defaults reviewed quarterly
- Tax year parameters updated by January 31
- Methodology changes logged in Corrections Policy