Guide
San Diego's ADU bonus program in 2026: what changed and how many ADUs you can build
The short answer
The program did not end, but the City of San Diego narrowed it in 2025. A single-family lot can hold two ADUs and a JADU under the base rules, and the bonus program adds more only when you deed-restrict some ADUs as affordable, with a total cap of four, five or six ADUs and JADUs depending on lot size. The 2025 rules took effect on August 22, 2025 outside the Coastal Zone and still wait for Coastal Commission certification inside it.
Did the program end?
No. In early 2025 the City Council asked staff to come back with changes, at first including a repeal, and later with a plan to remove the program from eight low-density zones and tighten it everywhere else. In June 2025 HCD warned the City that the proposed changes raised concerns under state ADU law and could put its housing element commitments at risk.
The amendments the Council adopted in July 2025 kept the program and narrowed it. They took effect on August 22, 2025 everywhere except the Coastal Zone.
For scale: HCD's June 2025 letter put the program's output at 875 ADUs permitted since 2020, 368 of them with affordability restrictions, according to City staff.
The City Council introduced the ordinance, O-21989, on June 10, 2025 and passed it on July 22, 2025. Its official date of final passage, when the Mayor's signed copy reached the City Clerk, is July 23, 2025, the date HCD and the code's history note use. It took effect on August 22, 2025 outside the Coastal Overlay Zone.
How the bonus program works now
Start with the base rules. A lot with a house, or a planned one, in a single-family zone can have one ADU inside the house or an existing accessory structure, one attached or detached ADU, and one JADU. The bonus program adds ADUs on top of those.
- Affordable first. Each bonus ADU is paired with an ADU you deed-restrict as affordable to very low, low or moderate income households, at rents the code caps, for at least 10 years for very low or low income households and at least 15 years for moderate income households.
- Near transit you get more. Inside a Sustainable Development Area, the area within a set walking distance of a major transit stop, you can build one bonus ADU for every affordable ADU. Outside it, the most is one bonus ADU and one affordable ADU. The City's ZAPP map shows which side of the line your lot is on.
- An agreement with the San Diego Housing Commission, secured by a deed of trust, must be signed before the first building permit for an affordable or bonus ADU is issued.
- One more for accessibility. If at least two of the ADUs are affordable, you can add one market-rate ADU built to the accessibility chapter of the Building Code, with an accessible bathroom, kitchen and bedroom.
- The zone still rules. Multiple ADUs, bonus ones included, have to fit the zone's floor area ratio, height and lot coverage limits, though one ADU of 800 square feet or less may go over the floor area ratio.
The City's ADU page still says 15 years at every income level, but the Municipal Code cut the very low and low income term to 10 years in 2022.
How many ADUs you can build
| Lot area | ADUs and JADUs in total |
|---|---|
| 8,000 square feet or less | 4 |
| 8,001 to 10,000 square feet | 5 |
| 10,001 square feet or more | 6 |
The cap counts every ADU and JADU on the lot, not only the bonus ones. Lot area leaves out any environmentally sensitive lands, and for the floor area ratio no more than 8,000 square feet of lot area counts.
Here is how the numbers meet outside a Sustainable Development Area. The base rules allow two ADUs and a JADU, the program adds one affordable and one bonus ADU, and on a lot of 8,000 square feet or less the cap of four is reached before all five could be built.
What changed in 2025
| Change | What the amendments did |
|---|---|
| Where it applies | No bonus ADUs in the RS-1-1 to RS-1-4 and RS-1-8 to RS-1-11 zones, unless the lot sits in a High or Highest Resource opportunity area on the state Tax Credit Allocation Committee's map and the land use plan shows it as residential. |
| How many | A total cap by lot area. The City's November 2024 bulletin said the number of bonus ADUs inside a Sustainable Development Area was unlimited, within the zone's floor area, height and coverage limits. |
| Fire zones | In fire hazard zones the lot has to face an improved public street that offers two or more evacuation routes. A lot on a cul-de-sac, or with only one way in and out, is left out. The code says High or Very High zones, and the City's adopted fire map shows only Very High ones. |
| Parking | One off-street space for each affordable and bonus ADU outside a Transit Priority Area. |
| Sprinklers | Automatic fire sprinklers in every affordable and bonus ADU. |
| Trees | Two trees for every 5,000 square feet of lot area, and at least one. |
| A new fee | A Community Enhancement Fee on the floor area of the affordable and bonus ADUs, set by Council resolution. Very low and low income ADUs in the higher-resource opportunity areas are left out of the calculation. It applies whatever the ADU's size, and you pay it before you ask for the final inspection of your first affordable or bonus ADU. |
| Penalties | A minimum monthly penalty for each ADU if the affordability agreement is broken, on top of any fines in the agreement itself. |
| Selling an ADU | The same amendments created the City's ADU condominium rules. The separate-sale guide covers them, bonus ADUs included. |
A City news story from June 2025 said the fee applies only to ADUs under 750 square feet, but the code and the Council's fee resolution set no size limit. ADUs you build under state law, outside the program, don't pay it.
Fees on a bonus project
- Development Impact Fees. The City exempts ADUs under 750 square feet of gross floor area, and the first two ADUs on a lot whatever their size, counting the two smallest when there are more. Every ADU is exempt when the owner signs an affidavit to live on the property for at least three years from permit issuance.
- A project with more than one ADU pays the Regional Transportation Congestion Improvement Program fee.
- The Community Enhancement Fee applies to the affordable and bonus ADUs, as above.
- State law bars impact fees on an ADU with 750 square feet of interior livable space or less and scales them to the house above that. An ADU or JADU under 500 square feet of interior livable space does not trigger school fees.
- The amounts are in the City's Information Bulletin 501 and on its fees page.
These state fee rules have applied since January 1, 2026. SB 543 was signed on October 10, 2025, but it has no urgency clause, so it took effect at the start of the next year. Some summaries give the October date, which belongs to a different bill, AB 462.
If your lot is in the Coastal Zone
The 2025 amendments do not apply in the Coastal Overlay Zone until the Coastal Commission certifies them. The City filed them with the Commission on July 29, 2025. For the Commission's October 2025 meeting, its staff asked for up to a year more to review them, and the City asked the Commission to finish sooner. The City's code page still says certification is expected in 2026.
Older packages are in force on the coast. Housing Action Package 2.0, which also touched the bonus program, was certified there on March 11, 2026, and the 2024 code update followed on September 10, 2026. On a coastal lot that means the program before 2025: the lot-size cap doesn't apply, inside a Sustainable Development Area the zone's floor area, height and coverage are the only limit on bonus ADUs, and the 2025 rules on sprinklers, parking, street access and the new fee don't apply either.
The City's ADU bulletin (Information Bulletin 400, January 2026) still lists Housing Action Package 2.0 as not in effect on the coast, so ask the City at intake which version of the rules it is applying to your lot.
HCD's review of the 2025 ordinance
On October 6, 2025, HCD found the 2025 ordinance out of line with state ADU law on four points and gave the City until November 5, 2025 to respond.
- Fire sprinklers. HCD disagreed that a structure made of several attached ADUs always needs sprinklers when the main house does not.
- Size. An ADU detached from a multifamily building should have no maximum floor area.
- Setbacks. The code's wording mixes up setbacks with fire separation distance.
- Separate sale. The rules for a sale by a nonprofit leave out tenancy in common terms state law requires for agreements recorded after 2021.
We found no published response or follow-up letter. The September 2026 printing of the Municipal Code still reads as HCD quoted it on these points, though a 2026 update that took effect on July 15, 2026 changed other parts of the same section. None of the four findings is about the bonus caps.
What changes the answer
The rules above are the City of San Diego's, for lots in single-family zones. These are the cases where the answer moves.
The Coastal Overlay Zone
The 2025 caps and limits are not in effect there yet, and which earlier version applies is one of the open questions above. A Coastal Development Permit is also required for most new ADUs in that zone.
Fire hazard zones
In the City's Very High fire hazard zones, the only kind its map shows, bonus ADUs need a lot on an improved public street with two evacuation routes, not on a cul-de-sac and not with a single way in and out.
Low-density zones and sensitive land
Eight of the lowest-density RS-1 zones are out of the program unless the lot is in a High or Highest Resource opportunity area. Environmentally sensitive lands come off the lot area that sets the cap.
Multi-dwelling zones
The lot-size cap is for zones that allow a single house but not apartments. With an existing multifamily building, for example, the City allows up to eight detached ADUs, never more than the number of existing units.
Another city, or the unincorporated County
The ADU Home Density Bonus Program is the City of San Diego's own, set in its Municipal Code. The 17 other cities and the County each have their own ADU rules within state law.
A homeowners association
State law voids HOA rules that prohibit or unreasonably restrict an ADU or JADU on a lot zoned for single-family homes, and from January 1, 2027 on a lot zoned to allow one. An HOA may still set limited objective standards, such as materials or style.
Utilities
For an ADU that is not a conversion of existing space, a water or sewer provider may require its own connection, with a connection fee or capacity charge in proportion to the unit. On a lot with several ADUs that adds up.
Next steps
Check your zone and transit area, count the units your lot can hold, then price them.