Sources and methods
The evidence should be as clear as the mission.
We distinguish published observations, research estimates and illustrative assumptions. The model shows how purchase assistance could change a payment. It does not establish a household's eligibility, a lender's approval or the program's future results.
Review date: September 30, 2026. Selected headline observations were checked against the primary sources below, and the payment and funding calculations were independently recomputed. Sources update on different schedules; these are dated comparisons, not a live data feed.
The observations behind the example
| Measure | Observation used | What it represents | Primary source |
|---|---|---|---|
| Median weekly earnings | Q1 2020: $957 Q2 2026: $1,251 | Nominal weekly earnings of full-time wage and salary workers aged 16 and over; not seasonally adjusted. An individual worker measure, not household income. Q4 2025 has no published value in this series. | BLS via FRED |
| National home price index | January 2020: 212.360 June 2026: 336.663 | S&P Cotality Case-Shiller U.S. National Home Price Index, January 2000 = 100, not seasonally adjusted. A repeat-sales index, not the median sale price or a specific home's valuation. | S&P via FRED |
| Mortgage rate | January 2020: 3.62% rounded baseline September 24, 2026: 7.03% survey average | Freddie Mac 30-year fixed-rate survey. The worked example deliberately uses 7%, a rounded scenario assumption; an individual borrower may receive a different rate. | Historical PMMS via FRED · Freddie Mac |
| Earnings by age | Q1 2020 → Q2 2026 25–34: $872 → $1,160 16–24: $588 → $806 | Median weekly earnings for full-time wage and salary workers in each age group, not seasonally adjusted. These are changing groups of workers, not the same people followed over time. | BLS Q1 2020 · BLS Table 3 |
| First-time buyers | 21% of buyers; median age 40; median down payment 10% | NAR's 2025 survey covers purchases of primary residences from July 2024 through June 2025. Its buyer sample is not all households or all renters. | NAR 2025 buyer profile |
| Homeownership under age 35 | Q2 2026: 35.2% Q2 2025: 36.4% | Census estimate for households whose householder is under 35. The Q2 2026 rate has a ±0.7 percentage-point margin of error at 90% confidence. It is not the share of individual young adults who own. | Census HVS Table 7, Q2 2026 |
| Reasons for renting | 2024: down payment 68%; monthly payment 49%; qualifying 42% | Federal Reserve SHED, all renters. Respondents could choose more than one reason. The responses do not measure demand for this program. | Federal Reserve, Table 40 |
What the model holds constant
A $500,000 purchase, a 20% down payment and a 30-year fixed mortgage are assumptions. The 2020 comparison rescales that example using the national price index. The “earnings-supported” payment preserves the example's 2020 payment-to-earnings share after applying observed earnings growth.
It is a historical comparison, not a lender's affordability standard. Another benchmark produces another gap. The worked example includes alternative benchmark years and a calculator to explore those choices.
- Principal and interest only. Taxes, insurance, mortgage insurance, maintenance, association fees, utilities and closing costs are excluded.
- Individual earnings cannot substitute for a household's income, debts, savings or number of earners.
- National averages cannot establish a local purchase price or a fair appraisal.
- The 20% down payment is an assumption, not a claim that buyers must put 20% down.
- The historical chart combines monthly prices, quarterly earnings and mortgage rates. Its periods and benchmarks are approximations, with values rounded for display.
The payment calculation
Monthly rate r = annual rate as a decimal ÷ 12
Payment M = L × r ÷ (1 − (1 + r)^−360)
2020 price P₀ = 500,000 × 212.360 ÷ 336.663
= $315,389.57
2020 payment M₀ = M(0.8 × P₀, 3.62%) = $1,149.96
2026 scenario M₁ = M(400,000, 7%) = $2,661.21
Reference T = M₀ × 1,251 ÷ 957 = $1,503.24
Monthly gap G = M₁ − T = $1,157.97
Principal PV(G, 7%, 360 months) = $174,051.63
Payment share M ÷ (weekly earnings × 52 ÷ 12)Earnings growth: 1,251 ÷ 957 − 1 = 30.721%. Price-index growth: 336.663 ÷ 212.360 − 1 = 58.534%. The modeled payment increases 131.417%, reflecting both the indexed price change and the selected mortgage rates.
Cash commitments are different from present value.
Cash commitment adds the dollars promised across time. Present value discounts future payments for comparison. Discounting a promise does not reduce the cash needed to fulfill it unless a separate, reliable funding source makes up the difference.
| Scenario | Total cash payments | Present value at 7% |
|---|---|---|
| Five-year flat subsidy | $69,478 | $58,480 |
| Declining subsidy under the earnings assumption | $101,925 | $75,199 |
Flat cash G × 60 Flat PV G × (1 − (1 + 0.07/12)^−60) ÷ (0.07/12) Growth g = (1,251 ÷ 957)^(1 ÷ 6.25) − 1 ≈ 4.38%/year Monthly aid Sₘ = max(0, M₁ − T × (1 + g)^((m − 1)/12)) Declining cash Σ Sₘ, for m = 1…360 Declining PV Σ Sₘ ÷ (1 + 0.07/12)^m
Payments occur at month-end. The first declining payment uses starting earnings; earnings grow between payments. The 4.38% annual path is an extrapolation of the selected historical interval, not a forecast of any household's wages. Slower growth would require more support to maintain the same share. The funding calculator reserves nominal commitments and assumes no investment earnings.
Repayment, purchasing power and uncertainty
The funding calculator deducts the entered operating share and reserve share, then rounds the number of complete household commitments down. For recoverable assistance, it applies an assumed loss percentage and repayment year. Those are scenarios, not estimates of actual losses or collections.
“Purchasing power at the start” divides future repayment by (1 + inflation rate)years. It uses a fixed 2.491409% annual inflation assumption, displayed as 2.49%. That is an inflation adjustment, not discounting at the 7% mortgage rate. Future-household equivalents assume the same inflation-adjusted assistance cost and omit future administration costs.
The inflation assumption came from a September 26, 2026 Truflation snapshot in the original research. The public source did not expose that historical numerical observation during this review. It is retained only as an explicit calculator assumption, not a verified current inflation reading or a forecast. The cumulative Truflation comparison is not used in our headline evidence.
How to read the research
Freddie Mac's housing shortage estimate refers to Q3 2024. FHFA's lock-in estimate refers to foregone sales from Q2 2022 through Q2 2024. Neither is a fresh 2026 count, and they measure different things. The research page keeps study findings separate from our program judgments.
Published estimates can disagree. We include the September 2026 Help to Buy evaluation alongside the earlier study because the London price result is sensitive to the analysis. Program design should respond to that uncertainty rather than hide it.
Earlier historical series remain in the benchmark tools for comparison. This review does not claim that every historical data point or every cited study was independently replicated. The source links, dates and limitations let readers examine the parts that matter to them.
Read the research and its program implications · Truflation source