What Is a Short-Term Rental ADU?

Key takeaways

• A short-term rental means guests stay for nights or weeks. They are not tenants who live there.
• In California, every junior ADU must be rented for more than 30 days. Short stays are out ³.
• ADUs approved under § 66323 must also be rented for more than 30 days ².
• For other ADUs, the city may require 30 days or longer ¹. Many cities do.
• “30 days or longer” and “longer than 30 days” are different. A 30-day stay passes one and fails the other.
• Being able to list on a platform does not make it legal. Your city decides.
• This page is held for expert review. It is education, not legal advice.

What a short-term rental ADU means, in plain English

You rent your backyard unit to travelers, one booking at a time. A family stays for a weekend. A nurse stays for two weeks. Then they leave, and the next guest comes. That is a short-term rental.

The guest has a home somewhere else. They are visiting. That is what makes them a guest and not a tenant.

The opposite is a tenant who moves in and stays for months. See the long-term rental ADU page for that path.

Why it matters to you

Short stays can look like more money per night. But if the rules do not allow them, you can face fines, a lost permit or a forced change of plan after you have built.

The rules are often set before you build. Your approval path can lock in a minimum rental term. So the time to check is at the planning stage, not after the unit is done.

Lenders and insurers also care. A policy written for a home may not cover paying guests.

How short-term rules work across the US

The length of the stay changes almost everything else. It decides which zoning use applies, whether the occupant is a tenant or a guest, which taxes the city collects, and what your insurer and lender think you are doing with the property.

Many US cities regulate short-term rentals apart from housing. They use registration, permits, caps, primary-residence rules or bans in some zones. ADUs are often singled out because they were legalized to add long-term homes. HyreADU does not summarize every state; see ADU laws by state and your own city’s code.

California: which section applies to your ADU

The 30-day wording trap

The two phrasings are not the same. Section 66315 allows a city to require terms of “30 days or longer”. Sections 66323(e) and 66333(g) require a term “longer than 30 days”.

A lease of exactly 30 days meets the first and fails the second. If your unit was approved under § 66323 or is a junior ADU, plan on stays of at least 31 days.

State law sets what a city may or must require. It does not promise that short stays are allowed.

A city with no ADU rental-term rule may still limit short stays in any home through a separate ordinance, permit system or zoning.

That is why “can I Airbnb my ADU?” almost always ends at the local code. The ADU short-term rental rules research page tracks how the layers interact.

How long is long enough? Stay lengths tested

Guest or tenant: why the 30-day line keeps coming up

California law ties several things to a stay of 30 days. Cities and counties may charge a lodging tax, often called a transient occupancy tax, on a stay in a “tourist home or house” or other lodging, unless the stay is longer than 30 days ⁴.

The state’s landlord-tenant chapter of the Civil Code also leaves out a person in “transient occupancy” in a hotel or similar place when that stay is subject to the lodging tax ⁵. In plain words: a short paid stay is treated more like a hotel visit than a tenancy.

So a stay over 30 days usually moves the occupant toward tenant status. That brings tenant protections. Read the ADU rent control rules before you plan a mix of short and mid-length stays.

How to find out if your ADU can be a short-term rental

1. Find how the ADU was approved. The permit or approval letter names the process, which tells you whether § 66315, § 66323 or § 66333 governs it.
2. Read the conditions of approval and any recorded covenant on the title for a rental-term limit.
3. Read your city or county ADU ordinance for a rental-term clause.
4. Read the separate short-term rental ordinance: registration, primary-residence rules, caps and taxes.
5. Check HOA rules, your insurance policy and your mortgage terms. Each can restrict short-term use on its own.
6. If anything is unclear, ask the planning department in writing. It decides, not the platform or a listing agent.

Worked example: three ADUs, three answers

Three hypothetical California owners. The facts are made up to show how the approval path changes the answer. Local rules could make any answer stricter.

Owner C is the only case where state ADU law leaves room. Even then, the city’s short-term rental ordinance and HOA rules still apply ^{1 2 3}.

Where you will see these rules

• The approval letter or permit: often states “rentals of 30 days or longer” or “longer than 30 days.”
• A recorded deed restriction: some cities record the rental term on title.
• The city’s short-term rental ordinance: registration, caps and primary-residence rules.
• A city tax notice: lodging tax registration if short stays are allowed.
• Your HOA rules, insurance policy and mortgage: each may restrict rentals.

Costs and what drives them

HyreADU does not publish typical short-term rental income or costs. They swing too much by city and season to be honest about.

The main cost drivers are cleaning between stays, furnishing, platform fees, lodging tax where it applies, permit and registration fees, and insurance that covers paying guests. Empty nights between bookings also cut income.

Federal tax rules add a twist. The IRS treats a unit as used as a home if your own use is more than 14 days or more than 10% of the days it is rented at a fair price, whichever is greater.

Then costs must be split between rental and personal use ⁶. Ask a tax preparer how this fits your case.

Benefits and limits, where both are allowed

Short-term, mid-term and long-term compared

Common mistakes and myths

Myth “State ADU law protects my right to Airbnb my ADU.”

Reality California law lets or makes local agencies require longer rental terms. It does not guarantee short stays ^{1 2}.

Myth “State law bans short stays in every California ADU.”

Reality Not quite. The longer-than-30-day rule binds JADUs and § 66323 ADUs. For § 66314 ADUs, it is the city’s choice ¹.

Myth “A 30-day booking is always long-term.”

Reality Not where the rule says “longer than 30 days.” A 30-day term fails it ^{2 3}.

Myth “If the platform lets me list it, it is legal.”

Reality Listing sites do not decide land use. The city or county does.

What to ask your city

• Under which section was my ADU approved: § 66314, § 66323 or the JADU ordinance?
• Does the city require ADU rentals of 30 days or longer under § 66315?
• Is there a deed restriction on my title about rental terms?
• Does the short-term rental ordinance allow stays in an ADU at all?
• Is a permit, registration or primary-residence rule required?
• Do I need to register for lodging tax?

Checklist for your project

1. Decide early if you want short stays. Raise it with the planner before you apply.
2. Note the approval path on your permit and the rental term it carries.
3. Get the answer in writing from the planning department.
4. Check HOA rules, your loan and your insurer.
5. If short stays are out, run the long-term numbers with the rent estimator.
6. If short stays are allowed, register, collect lodging tax and keep records.
7. Recheck the city ordinance each year; these rules change often.

Where the rental-term rule comes from

1. State ADU law (§§ 66315, 66323, 66333)
2. approval path for your ADU
3. conditions of approval
4. city short-term rental ordinance
5. what you may rent

Related research and tools

• ADU rental hubLong-term and short-term renting
• ADU rental income research
• Insuring an ADUWhat changes when guests stay
• California ADU ordinance tracker
• ADU regulations hub

Related terms

Long-Term Rental ADU

A long-term rental ADU is an accessory dwelling unit leased to a tenant who lives in it as their home, usually for a month-to-month or fixed-term lease, rather than rented to short-stay guests.

ADU Rental

Renting out an ADU, long-term to a tenant or, where local rules allow, short-term to guests.

ADU Rental Income

The rent an ADU earns, before or after vacancy, maintenance, insurance and taxes.

ADU ROI

ADU ROI (return on investment) is the money an accessory dwelling unit earns or adds in value, expressed as a percentage of what it cost to build.

Local ADU Ordinance

A local ADU ordinance is the section of a city or county's zoning code that sets the rules for accessory dwelling units in that jurisdiction: where they are allowed, how big and tall they can be, setbacks, design standards and the application process.

California ADU Law

California ADU law is the set of state statutes, now in Chapter 13 of the Government Code (Sections 66310 to 66342), that tells every city and county in California what it must allow for accessory dwelling units and junior ADUs, and what it may not require.

Junior ADU

A junior ADU (JADU) is a small home of no more than 500 square feet carved out of an existing or proposed single-family house, with its own entrance and an efficiency kitchen, and permission to share the main home’s bathroom.

Ministerial Approval

Ministerial approval is a permit decision in which an official checks an application against fixed, objective standards and must approve it if they are met, with no public hearing and no discretion to deny it on judgment.

ADU Rental Agreement

An ADU rental agreement is the written lease between the owner of an accessory dwelling unit and the tenant who lives in it, setting the rent, the term and the house rules for a home that shares a lot with the owner’s house.

Also referenced from: ADU Owner-Occupancy Requirement, ADU ROI, ADU Rental Agreement, Long-Term Rental ADU