Why this matters before you're under contract
An unpermitted second unit isn't automatically a problem — plenty of homes have them, and California's legalization framework (see our guide to legalizing an unpermitted ADU) makes fixing it more realistic than it used to be. But as a buyer, you want to know what you're actually getting before closing, not discover it afterward.
What to check before you write an offer
How this can affect your financing
Lenders and appraisers generally don't credit unpermitted square footage the same way they credit legal living space, which can affect your appraisal and, in some cases, your loan approval. If part of your purchase decision depends on the unit's value or rental income potential, confirm with your lender directly how they'll treat it — don't assume it counts the way a legal ADU would. See our guide to how lenders evaluate ADU rental income for how this works for legal units, as a point of comparison.
Negotiating around an unpermitted unit
- Ask for a price adjustment reflecting the cost and effort of legalization, if that's something you'd want to pursue after closing.
- Request seller disclosure in writing of everything they know about the unit's history, rather than relying on verbal assurances.
- Consider making legalization a contingency or at minimum budget for it separately from your purchase price — see our legalization guide for what that process generally involves and costs.
This isn't legal or real estate advice
This page describes general considerations, not advice for your specific transaction. A real estate agent and, where the situation is complex, a real estate attorney are the right resources for negotiating around a specific unpermitted structure.
Frequently asked questions
Not necessarily — many unpermitted units can be legalized under California's current framework. The key is knowing about it before closing, understanding roughly what legalization would involve, and factoring that into your offer rather than being surprised later.
Often, yes — appraisers typically research permit history as part of their process, and discrepancies between what they find and what's being marketed can surface during underwriting. It's better to know this upfront than have it surface as a surprise mid-transaction.
Often yes, especially for units built before 2020 — see our guide to legalizing an unpermitted ADU for how California's current legalization framework generally works.