Stacking ADU Grants and Loans in California, Washington and Massachusetts — Casita & Capital
Updated November 2026
ADU programs change with appropriations, local allocations and application windows. A statewide law permitting ADUs does not mean a statewide construction grant is currently funded. Verify an active program before making a nonrefundable commitment.
Verify jurisdiction and eligible costs
For California, consult CalHFA; for Washington, consult the Department of Commerce; for Massachusetts, consult MassHousing. Local governments may administer separate loans or grants with income, owner-occupancy, rent or affordability restrictions.
Ask whether assistance covers design and permitting only or actual construction, whether reimbursement occurs after payment and whether a lien is recorded. A grant with recapture conditions is not equivalent to unrestricted cash. Confirm whether the first lender accepts the assistance terms.
Prevent double reimbursement
Build a cost ledger identifying which source pays each invoice. Two programs may prohibit paying the same expense twice or require other assistance to be disclosed. Account for delayed reimbursement, affordability covenants and repayment on sale or refinance. Written stacking approval is more reliable than assuming two individually available programs can be combined.
Documents and decision checkpoints
| Review item | Evidence to request | Why it matters |
|---|---|---|
| Eligibility | Written program and property requirements | A loan officer's initial discussion is not final approval |
| Monthly cost | Itemized payment including insurance and subordinate debt | Principal and interest alone understate ownership costs |
| Closing cash | Loan Estimate, credits and source-of-funds records | A credit cannot be counted twice |
| Exit terms | Payoff, prepayment and lien-release provisions | Selling or refinancing may trigger additional costs |
Compare written offers using the same loan amount, term and lock period. Ask which conditions remain outstanding and who must clear each one before closing. If a fee or qualification rule differs from an agency guide, request the lender's written explanation; lenders may impose additional requirements. Do not send tax returns, account numbers or court records to an editorial inbox.
Plan the payment and verify the source
Use the monthly payment calculator for principal, interest, taxes and insurance, and the closing cost estimator for upfront cash. A calculator estimate is not a credit decision or a rate lock. Keep HOA dues, maintenance and any second mortgage separate if the calculator does not include them.
Review the CFPB mortgage resources and HUD housing resources alongside CFPB and VA Home Loans. Verify the current publication date and the rules effective for your transaction. Agency eligibility, lender approval and legal ownership are separate determinations. This guide is educational, not an offer to lend or individualized legal or tax advice.
Compare Current Mortgage Rates
Compare current APRs, points, fees, and estimated monthly payments from participating lenders below.
Loan Program Comparison: 2026 Benchmarks
Stacking ADU Grants and Loans in California, Washington and Massachusetts — Choose a mortgage by comparing eligibility, upfront cash and total monthly costs, not the advertised rate alone. Conventional, FHA, VA and USDA serve different borrowers. Confirm county limits, taxes, insurance and lender requirements before comparing personalized Loan Estimates for your household.
Historical 2025 one-unit comparison: conforming $832,750; FHA floor $541,287. County and unit-count limits can differ.
| Loan program | Down payment / equity | 2026 one-unit baseline | Costs and page-specific comparison |
|---|---|---|---|
| Conventional | 3%–5% subject to eligibility | $832,750 | PMI generally below 20% down |
| FHA | 3.5% at 580+; 10% at 500–579 | $541,287 floor | 1.75% upfront MIP; 0.55% annual for >95% LTV, base loan ≤$726,200, term >15 years |
| VA | 0% for eligible borrowers | No VA limit with full entitlement | No monthly PMI; funding fee unless exempt |
| USDA | 0% for eligible borrowers | Income, address and repayment eligibility | Guarantee and annual fees; confirm current schedule |
| Jumbo | Lender-specific cash and reserves | Above applicable conforming limit | Lender-specific pricing and insurance |
| Home Equity / Refinance | Equity and underwriting dependent | Property and lender dependent | Compare closing costs, term and break-even |
Sources: FHFA limits; HUD FHA limits.
Editorial Methodology & Primary Sources
Verification date: Not recorded; check the primary source and lender timestamp before relying on an estimate.
Rate comparisons use participating lender feeds, not a whole-market survey or guaranteed offers. Freddie Mac PMMS is a market benchmark, not a personalized quote. Calculator models rely on published regulatory formulas and disclosed assumptions rather than fabricated first-person loan testing.
Monthly principal and interest use the amortization formula P × r / (1 − (1 + r)−n), where r is the monthly note rate and n is the number of payments; at zero interest use P / n. PITI adds monthly property taxes and homeowners insurance; PMI is separate. APR includes applicable finance charges under Regulation Z and is not the note rate used for payments. Compare lender Loan Estimates for actual APR and fees.
- Consumer Financial Protection Bureau (CFPB) — Loan Estimates, APR and borrower disclosures; Regulation Z.
- U.S. Department of Housing and Urban Development (HUD / FHA) — FHA program guidance.
- U.S. Department of Veterans Affairs (VA) — VA loan eligibility and benefits.
- Freddie Mac Primary Mortgage Market Survey (PMMS) — published rate benchmarks.
- U.S. Census state tax collections — state property tax benchmarks; confirm parcel-specific assessments and exemptions with the state revenue department and local assessor.
- CFPB — state housing finance and property tax authority.
- VA Home Loans — state housing finance and property tax authority.
The payment snapshot uses illustrative annual taxes of 1% of home price, $1,200 insurance and 0.5% PMI below 20% down, not verified local quotes. Other calculators disclose their inputs and assumptions. Published guidance and lender feeds may change independently; confirm current program rules, taxes and offers before a decision.