By ADU Scope editorial team ยท Last verified: October 2026
ADU rental income can help you qualify for a mortgage, but only inside strict limits. Freddie Mac counts at most 75% of a documented lease. In addition, it caps rent at 30% of the income used to qualify. FHA goes further and allows projected rent from an appraisal rent schedule. For conventional loans, however, do not assume a lender accepts a rent estimate for an unbuilt ADU.
This is general information, not financial advice. In fact, rules differ by lender and change often. So confirm every detail with a licensed loan officer first.
How Freddie Mac counts ADU rental income
Freddie Mac publishes the clearest conventional rule. Its ADU fact sheet sets these conditions for ADU rental income.
| Rule | What Freddie Mac says |
|---|---|
| Share of the lease | Rental income documented with a lease must not exceed 75% of the lease amount |
| Cap on rent | Qualifying rental income cannot exceed 30% of total income used to qualify |
| Property | One-unit primary residence with one ADU that is legal, legal non-conforming or has no zoning |
| Transactions | Purchase or no cash-out refinance only |
| Appraisal | At least one comparable sale with an ADU and at least three comparable rentals, one of them a rented ADU |
Two points matter in practice. First, the 75% factor covers vacancy and expenses, so a $2,000 lease counts as $1,500. Second, the cap means rent can never carry an application alone. Your regular income must supply at least 70% of the total.
The fact sheet describes lease-documented income only. Moreover, it does not mention projected rent. We therefore cannot confirm that Freddie Mac counts rent from a unit that does not exist yet.
Worked example: ADU rental income and the 30% cap
This example is hypothetical. It applies Freddie Mac’s 75% factor and 30% cap as quoted above, and your lender may calculate differently. The inputs are a documented ADU lease of $2,000 per month and three possible levels of other qualifying income.
| Other monthly income | Counted rent (75% of lease) | Total income | 30% cap | Rent that counts |
|---|---|---|---|---|
| $8,000 | $1,500 | $9,500 | $2,850 | $1,500 |
| $5,000 | $1,500 | $6,500 | $1,950 | $1,500 |
| $3,000 | $1,500 | $4,500 | $1,350 | $1,350 |
In the third row, the cap trims $150 of rent. The break-even point is simple: $1,500 equals 30% of $5,000, so the cap stops binding once other income reaches $3,500. We read the cap as a share of total income including the rent. Therefore, ask your lender to confirm that reading.
As a result, ADU rent helps most when your regular income is moderate to high. However, it cannot replace a missing job. It also lowers your debt-to-income ratio only by the counted amount, not the full lease.
How FHA treats ADU rental income
FHA is more flexible on timing. HUD Mortgagee Letter 2023-17 allows ADU rental income as effective income for forward mortgages. Per the letter, the income must not exceed 30% of the total monthly effective income used to qualify.
With no rental history, the lender needs an appraisal and a comparable rent schedule showing fair market rent. As a result, projected rent can count on FHA. The letter applies 75% of the lesser of market rent or the lease.
- Standard FHA loan: 75% of the lesser of appraised market rent or the lease, within the 30% cap.
- 203(k) rehabilitation loan: 50% of that lesser amount. ADUs are eligible improvements under 203(k), and on a $2,000 rent the counted figure falls to $1,000.
- Cash-out refinance: ADU rent cannot qualify you.
- Reserves: two months of PITI after closing for a one-unit property with an ADU.
FHA also has county loan limits that we did not verify here. Check HUD’s FHA mortgage limits lookup for your county before you plan around a specific loan size.
Where Fannie Mae stands on ADU rental income
Fannie Mae says ADUs can be financed with any Selling Guide loan product. Its HomeStyle Renovation product lets a borrower construct or install a new ADU on a one-unit property. For HomeReady, it says borrowers with an existing ADU can include rental income to help qualify.
Fannie Mae also states that ADUs do not qualify with a two- to four-unit dwelling. They do not qualify when a manufactured home is the primary residence, and multiple ADUs are out too.
We could not verify a Fannie Mae percentage or cap for ADU rental income, so we do not quote one. Overall, the rules differ by loan type. Ask your lender, and point them to Selling Guide sections B3-3.1-08 and B3-3.8-01.
Can projected ADU rental income help before the ADU exists?
The honest answer depends on the program. FHA allows prospective rent supported by an appraisal rent schedule. For conventional loans, Freddie Mac’s published rule rests on a lease. We found no confirmation that projected rent for an unbuilt ADU counts, so do not plan your budget around it.
Timing therefore matters more than the rule. If you need the rent to qualify for the construction financing itself, you may be disappointed. If you only need it for a later refinance, a signed lease on a finished unit is far stronger proof. Freddie Mac’s rule covers purchases and no-cash-out refinances only. Also, confirm how your lender classifies the refinance.
Budget comes first, though. Before you test any lender, check the full price in how much an ADU costs in California. Then read how ADU construction loans release funds during the build.
Questions to ask your lender about ADU rental income
- Do you count ADU rental income for this loan type, and at what percentage?
- Do you accept projected rent, or only a signed lease?
- Does the 30% cap apply to my loan, and how do you calculate it?
- Will my refinance count as no cash-out if it pays off the construction loan?
- Do you need a full appraisal with ADU comparables, and does my area have them?
- Does my ADU meet your rules on separate entrances and size?
Owner-occupancy can also matter for these loans, so review owner-occupancy rules for ADUs in your state. The full menu of products sits in our guide to how to finance an ADU.
A practical order of operations
Most owners get better results by sequencing the steps. First, decide how you will pay for construction without counting on future rent. Then treat rent as a bonus for the refinance or the next purchase.
- Ask two or three lenders which programs they offer and whether any accept projected rent.
- Price the build using realistic numbers from our ADU budget breakdown.
- Fund construction with sources that do not depend on the rent, such as savings, a HELOC or a construction loan.
- Sign a lease once the unit passes final inspection, then keep the lease and payment records.
- Refinance only after you compare the new rate and closing costs with your current loan.
This order protects you if the rent comes in lower than expected. In short, a lease on a finished unit is proof, while a projection is only a promise.
How a lender may stress-test ADU rent
Lenders rarely accept a rent figure at face value. They compare your number with appraiser data and apply their own haircut. For example, a $2,000 market rent under FHA’s standard rule counts as $1,500, while a lender that uses the 203(k) rule counts $1,000.
Hypothetical case: your regular income is $4,000 per month and you hold a $2,000 lease. At 75%, counted rent is $1,500 and total income is $5,500. The 30% cap is $1,650, so the full $1,500 counts. At 50%, counted rent is $1,000, and your qualifying income falls to $5,000. The method changes the result by $500 per month.
FAQ on ADU rental income and loan qualification
Does ADU rental income count as income for a mortgage?
Yes, in limited ways. Freddie Mac counts lease-documented rent at up to 75% of the lease, within a 30% cap. FHA counts rent under similar limits, and it also accepts projected rent supported by an appraisal.
Does the ADU have to be legal?
Freddie Mac’s rule requires a unit that is legal, legal non-conforming or located where no zoning applies. Unpermitted units are a poor foundation for any loan.
Can I use ADU rental income on a cash-out refinance?
Not under Freddie Mac’s rule or FHA’s. Both exclude cash-out refinances. See our comparison of cash-out refinance vs. HELOC for an ADU for other routes.