In most of the country you cannot sell an accessory dwelling unit separately from the main house, because property law treats the lot and everything built on it as one legal interest. A handful of states have opened a narrow path: convert the property into a two-unit condominium, get your lender’s written consent, and each unit becomes its own sellable interest. Selling an ADU separately from the main house is only realistic if your state has passed a specific separate-conveyance statute and your local jurisdiction has implemented it.
Why You Can’t Just Sell It
A parcel of land and every permanent structure on it form a single legal interest. The deed covers the ground, the house, the ADU, the garage, and the landscaping together. When you took out your mortgage, all of that became the collateral. Handing someone the keys and a deed to just the backyard cottage would create a title defect and almost certainly put your loan in default.
The traditional workaround is subdividing the lot, drawing a new property line so each structure sits on its own recognized parcel. Residential zoning usually blocks this. Minimum lot sizes, setbacks, and density limits mean a typical urban lot that barely fits one house will not qualify as two. That is the wall homeowners hit, and it is what the newer state laws are designed to get around.
Where It’s Currently Allowed
As of early 2026, only a few states have passed laws explicitly authorizing separate ADU sales. California’s Assembly Bill 1033, effective in 2024, is the most detailed framework and has served as a model. Washington authorized ADU sales as condominiums through HB 1337. Other states have introduced similar bills. Everywhere else, the ADU and the main house remain legally inseparable no matter how physically independent the ADU is.
Before spending a dollar on this, call your local planning department and confirm two things: that your state has a separate-conveyance statute, and that your city or county has adopted the local ordinance needed to actually use it. State authorization alone is often not enough.
How the Condominium Conversion Works
Where separate sales are allowed, the legal tool is a condominium conversion, not a lot split. You reclassify the existing property as a two-unit condominium project. The main house becomes Unit A, the ADU becomes Unit B, and shared areas like the driveway and yard are owned jointly. The land stays whole; what changes is that each unit gets its own deed and title and can be bought, sold, and financed on its own. Because you are not creating new parcels, minimum lot size rules no longer block you.
CC&Rs for Shared Space
The conversion requires a set of covenants, conditions, and restrictions (CC&Rs) spelling out how the two owners share and maintain common areas. These documents define exclusive-use spaces, how repair costs for shared sewer lines and driveways get split, and what rules govern modifications. Sloppy CC&Rs lead to neighbor disputes that are expensive to unwind, so this is work for an attorney who handles common-interest developments.
A Two-Unit HOA
Even with only two owners, the conversion creates a homeowners association. The HOA collects dues, carries the master insurance policy, and provides a legal structure for resolving disputes. Bylaws set voting rights and financial obligations. A two-person HOA still needs a bank account, annual meetings, and whatever corporate formalities your state requires. Skipping those formalities can expose both owners to personal liability.
Getting Your Lender’s Consent
If there is a mortgage on the property, this is the step that decides whether the rest is possible. Your loan is secured by the entire parcel. Converting to condominiums and selling one unit changes the collateral, so the lienholder must give written consent before anything gets recorded.
Expect the lender to order a new appraisal to check that the loan-to-value ratio on the remaining unit stays acceptable. If it doesn’t, you may need to make a principal payment to bring it back into range. Some lenders simply refuse. There is no law requiring them to agree, and many have no internal procedure for this kind of request because it remains uncommon.
The Due-on-Sale Clause
Most mortgages include a due-on-sale clause letting the lender demand full repayment if you transfer any interest in the property. Federal law protects certain transfers from that clause, including transfers to a spouse, transfers into a living trust, and specific inheritance situations.1Office of the Law Revision Counsel. 12 U.S. Code 1701j-3 – Preemption of Due-on-Sale Prohibitions Selling an ADU as a condominium unit is not on that list. Proceeding without explicit lender approval could allow the lender to accelerate the whole loan balance. That is the reason consent comes first, before you commission surveys, maps, or legal drafting.
What the ADU Itself Has to Meet
Beyond lender approval, the ADU has to clear several physical and administrative bars before a jurisdiction will approve the conversion.
- Building code compliance. The ADU needs a finalized building permit and a certificate of occupancy. Unpermitted structures have to be brought up to code first. Some jurisdictions offer streamlined permitting for older unpermitted units, but expect inspections and possibly significant remediation costs.
- Separate utility service. Each unit needs independent or clearly metered water, electricity, and gas. If the ADU currently shares connections with the main house, you will need to coordinate with utilities to install separate meters or document a billing arrangement in the CC&Rs.
- Condominium map and site plan. A licensed surveyor prepares a condominium plan showing each unit’s boundaries, exclusive-use areas, and common spaces. This is the foundational document that gets recorded.
- JADU exclusion. Junior ADUs, meaning small units carved out of the existing home’s footprint like a converted garage, are generally not eligible for separate sale. The separate-conveyance pathway is for detached or otherwise physically distinct ADUs.
Parking rules vary. Some cities require dedicated off-street parking for the ADU once it becomes its own interest, even if none was required when it was built as an accessory structure. Check local requirements before assuming your current setup qualifies.
Insurance After the Split
Your existing homeowners policy will not carry over. The new two-unit HOA has to carry a master property policy covering the residential structures and common elements. Fannie Mae, whose guidelines most lenders follow, requires that master policy to provide replacement-cost coverage for at least 100 percent of the project improvements, with a maximum deductible of five percent of the total coverage amount and coverage written on a “Special” form or equivalent.2Fannie Mae. Master Property Insurance Requirements for Project Developments
On top of that, each unit owner typically carries an individual HO-6 policy for personal property, liability, and interior finishes the master policy does not cover. Cancel the old homeowners policy, buy the master policy through the HOA, and add the individual unit policy. Per unit, a two-unit master policy often costs more than the standard single-family policy it replaces.
Federal Tax Consequences
Selling a rental ADU triggers capital gains tax, and the rules are less forgiving than many owners assume. The Section 121 exclusion, which lets you exclude up to $250,000 in gain ($500,000 for joint filers) on the sale of a primary residence, does not automatically cover a structure used as a rental.3Office of the Law Revision Counsel. 26 USC 121 – Exclusion of Gain From Sale of Principal Residence
The IRS distinguishes between business use inside your home and a separate structure used for business or rental. When the ADU is a physically separate dwelling you have been renting, the gain allocable to it generally does not qualify for the Section 121 exclusion, and you also have to recapture any depreciation you previously claimed.4Internal Revenue Service. Publication 523, Selling Your Home A different calculation may apply if you lived in the ADU as your primary residence for at least two of the five years before the sale, but that is uncommon for owners selling a backyard rental.
Transfer taxes are the other cost layer. Most states and many localities charge a real estate transfer tax when property changes hands. Rates run from flat nominal fees to several percent of the sale price, and a few states charge nothing. Your closing agent can give you the exact figure.
Whether a Buyer Can Actually Finance It
The obstacle owners often miss is on the buyer side. Most ADU condominiums are brand-new, two-unit projects with no sales history, and lenders scrutinize small or new condo projects more heavily than established ones. Fannie Mae does waive the full project review for condo projects with two to four units, which removes one significant barrier, though the project still has to meet basic eligibility standards around structure type, evacuation orders, and the priority of the HOA’s assessment lien.5Fannie Mae. B4-2.1-02, Waiver of Project Review
FHA and VA loans add more complications. Each has its own condo project approval process, and a two-unit conversion created under a new state ADU law may not fit neatly into either framework. Buyers relying on government-backed financing should confirm project eligibility with their lender before anyone pays for an inspection or appraisal.
Recording and Reassessment
Once lender consent is in hand, inspections are done, and the CC&Rs, HOA documents, and condominium map are ready, everything gets filed with the county recorder. The condominium plan, CC&Rs, HOA bylaws, and new deeds record together. That recording is what actually severs the single interest and creates two independent ones.
After recording, the local tax assessor assigns separate parcel identification numbers, which means separate property tax bills and independent valuations. Expect a revaluation. The combined assessed value of two condo units often differs from the property’s prior single-family assessment. Processing times vary widely by jurisdiction; some owners report the full cycle taking several months from application to recorded documents.
Disclosures on That First Sale
Selling a newly converted ADU condo is not the same as selling an ordinary resale unit. Because you created the condominium, you are likely classified as a subdivider under your state’s common-interest development laws, which brings heightened disclosure duties. These typically include giving the buyer the HOA’s current budget, reserve study, and financial statements, plus a written statement of any known defects in the unit and the common areas. Specifics vary by state, but the first sale of a converted unit carries more disclosure burden than a normal resale, and missing those disclosures can give the buyer grounds to rescind or sue after closing. Have your attorney prepare the full disclosure package before the unit goes on the market.