---
title: "Self-employed mortgage affordability: 2-year income averaging with add-backs, the declining-income rule, front/back DTI limits, PMI-aware max-price solve."
method: POST
path: "/v1/mortgage-affordability"
tags: ["Real estate"]
---

# Self-employed mortgage affordability: 2-year income averaging with add-backs, the declining-income rule, front/back DTI limits, PMI-aware max-price solve.

`POST /v1/mortgage-affordability`

## Request

- Base URL: `` (relative, and it does not resolve against the document’s source URL)
- URL: `/v1/mortgage-affordability`
- Auth: none declared

Self-employed mortgage affordability: 2-year income averaging with add-backs, the declining-income rule, front/back DTI limits, PMI-aware max-price solve.

Payment: x402 ($0.05 USDC on eip155:8453). Call unpaid to receive an HTTP 402 with requirements, then retry with the PAYMENT-SIGNATURE header. Method: qualifying income = declining rule (year1 only if declining) else 2-yr average, both + add-backs; budget = min(frontDTI, backDTI - debts); P = (B + D*(k+pm)) / (k + pm + tr) with amortization factor k, PMI when LTV > 80%

## Request body

- object
  - `year1NetIncome` number, required
  - `year2NetIncome` number, required
  - `addBacks` number
  - `monthlyDebts` number
  - `downPayment` number
  - `interestRatePct` number
  - `termYears` 15 | 20 | 30
  - `propertyTaxPct` number
  - `annualInsurance` number
  - `monthlyHOA` number
  - `frontDTIPct` number
  - `backDTIPct` number
  - `pmiRatePct` number

## Response `200`

Verified result + provenance (formula, sources, reproducible SHA-256 hash).

## Other responses

- `400`: Invalid input (no charge) — body echoes the JSON Schema.
- `402`: Payment required — PAYMENT-REQUIRED header carries the x402 accepts[] quote.

---

[API](https://skmtc.dev/x402toll/apis/tollbooth-verified-calculators-for-ai-agents.md) · [All operations](https://skmtc.dev/x402toll/apis/tollbooth-verified-calculators-for-ai-agents/llms.txt) · [OpenAPI document](https://skmtc.dev/x402toll/apis/tollbooth-verified-calculators-for-ai-agents/revisions/60cb70a3e1a5?raw)