Hawaii SB 3202 (Act 39): Two ADUs Per Lot and the December 2026 County Deadline

Hawaii's S.B. 3202 (2024), enacted as Act 39, tells all four counties to open residentially zoned lots to at least two accessory dwelling units, with a compliance deadline of December 31, 2026 and an automatic consequence for counties that miss it. Two years on, the counties have split badly: Maui complied this month, Hawaii County went further back in 2024, and Honolulu's Council has asked the Legislature to repeal the mandate outright. Here is what Act 39 actually requires, where it does not reach, and why it probably does not help you with your HOA.

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First, the number. S.B. 3202 became Act 39, Session Laws of Hawaii 2024, approved May 28, 2024 [1]. A surprising amount of secondary writing, including testimony filed with county councils, calls it Act 46. If a summary you are reading cites Act 46, treat everything else in it as unverified.

Second, the scope. Act 39 is narrower than the headlines suggest. It applies only inside the state urban district, exempts special management areas and high-hazard areas, and does nothing at all about the covenants that actually govern most Hawaii subdivisions. The mandate is real, but the version circulating online is considerably more generous than the statute.

Act 39 at a Glance

Act 39 fact	What the statute says	Source
Session law	Act 39, SLH 2024 (S.B. 3202, SD2 HD1 CD1), approved May 28, 2024, effective on approval	[1]
Core mandate	Each county shall allow at least two accessory dwelling units, or the reasonable equivalent, on all residentially zoned lots	[1]
Alternative path	A county that declines the blanket rule must instead designate qualifying districts hitting specified housing-supply targets	[1]
County deadline	December 31, 2026	[1]
Backstop if missed	County cannot deny a permit for up to two ADUs for exceeding the unit cap, but may still deny on infrastructure, design, or development standards	[1]
Geographic limits	Does not apply outside the urban district, to county powers in special management areas, or in high natural-hazard areas	[1]
"Residentially zoned lot"	Districts principally reserved for single-family and two-family detached dwellings; excludes rural, low-density, and open-space districts	[1]
Private covenants	Void only if recorded after May 28, 2024; expressly does not apply to covenants recorded before	[1]
Long-term rentals	No county may prohibit using a dwelling unit as a separately leased long-term rental, "as defined by each county"	[1]
Vested rights	None created; counties keep the power to accept, review, approve, and deny applications	[1]

Bottom Line

Act 39 added a new section to HRS chapter 46 requiring every county to "adopt or amend ordinances defining reasonable standards that allow for the construction of at least two accessory dwelling units, or the reasonable equivalent, for residential use on all residentially zoned lots" [1]. That is the headline, and it is a genuine statewide preemption of local unit caps.

The phrase doing quiet work is "or the reasonable equivalent." Act 39 never defines it. A county can plausibly argue that an existing framework producing two extra units by another name already satisfies the statute, and at least one county appears to be resting on exactly that reading.

The deadline is December 31, 2026 [1]. Miss it and subsection (g) kicks in automatically: the county "shall not deny any permit application on the basis of exceeding the maximum number of housing units allowed" when an owner applies to build up to two ADUs. Read the rest of that sentence, though, because it ends with a proviso that a county "may deny a permit application on the basis of infrastructure, design, or development standards" [1]. The unit cap falls. Everything else stays.

Myth	Reality
"SB 3202 is Act 46."	It is Act 39, SLH 2024, approved May 28, 2024. [1]
"Act 39 voids HOA rules that block ADUs."	Only for covenants recorded after May 28, 2024. The statute says it "shall not apply to any private covenants recorded before the effective date." Existing CC&Rs are untouched. [1]
"Every residential lot in Hawaii gets two ADUs."	Only lots inside the urban district, outside SMA county jurisdiction and high-hazard areas, in districts reserved for single- and two-family dwellings. Rural and low-density districts are excluded by definition. [1]
"After December 31, 2026 my county has to approve two ADUs."	It cannot deny for exceeding the unit count. It can still deny on infrastructure, design, or development standards. [1]
"The mandate is dead because Honolulu opposed it."	Honolulu's Council asked the Legislature to repeal it, but Act 39 remains law and Maui adopted an ordinance under it in July 2026. [2][3]

Two Ways a County Can Comply

Most coverage describes Act 39 as a flat "two ADUs everywhere" rule. The statute is actually a choice between two routes, and which one your county takes changes whether your particular lot benefits.

Route one, subsection (b). The county adopts standards allowing at least two ADUs on all residentially zoned lots [1]. This is the simple, uniform version, and it is what Maui did.

Route two, subsection (c). A county that does not adopt the blanket rule must instead designate districts that authorize at least two ADUs per permitted existing single-family dwelling. Those districts have to be consistent with the county's general plan, reasonably distributed across its regional planning areas, and estimated to add development potential equal to half the county's projected five-year housing demand from the 2019 Hawaii Housing Planning Study. The county must also designate districts within reasonable walking distance of mass transit stations and of urban principal arterials inside a primary urban area or urban core [1].

There is a third obligation stacked on top for the largest county. Under subsection (d), a county with a population of 500,000 or more, which means Honolulu alone, must additionally add development potential in existing apartment or apartment mixed-use districts equal to its full projected five-year housing demand [1].

So a county can be fully compliant with Act 39 and still not allow two ADUs on your specific lot, if it took route two and your lot sits outside the designated districts. Before assuming the mandate reaches you, find out which route your county chose.

Where Act 39 Does Not Reach

This is the section most summaries skip, and it is where a lot of Hawaii homeowners will discover the law does nothing for them. Subsection (i) carves out three categories [1]:

• Any area outside the urban district established by HRS chapter 205. Hawaii sorts all land into urban, rural, agricultural, and conservation districts at the state level. Act 39 stops at the urban district boundary, which excludes large amounts of residential land on Hawaii Island and Kauai.
• County powers within special management areas delineated under chapter 205A. The SMA is the coastal zone. Where a county is exercising SMA authority, Act 39 does not constrain it.
• Any urban-district area a county deems at high risk of a natural hazard such as flooding, lava, or fire, based on current federal or state data and maps [1].

That third carve-out deserves attention because the county makes the determination. Hawaii has extensive FEMA flood mapping, USGS lava-zone designations, and post-2023 wildfire-risk mapping. A county inclined to limit the mandate's footprint has a defensible tool for doing it.

The definition in subsection (k) narrows things further. A "residentially zoned lot" means a zoning lot in a district "principally reserved for single-family and two-family detached dwellings," and it expressly "does not include a lot in a county zoning district that is intended for rural, low density residential development, and open space preservation" [1]. Country-style residential zoning is out.

Two more limits are worth knowing. Subsection (f) preserves a county's ability to deny permits where there is insufficient utility infrastructure to serve the added demand, and subsection (j) states that neither the section nor any permit issued under it creates vested rights, and that it does not preempt a county's ability to accept, review, approve, and deny applications [1]. Act 39 lowers the zoning wall. It does not hand you an approval.

County-by-County Status, July 2026

The four counties have responded very differently, and where you own property matters more than the state mandate does. Status below is as of July 2026 and will keep moving.

County	Where it stands	Detail
Maui	Ordinance adopted	Bill 78 (2026) took effect July 8, 2026, allowing up to two accessory dwellings plus the primary home on residentially zoned lots across Maui, Molokaʻi, and Lānaʻi [2]
Hawaii	Went further, earlier	Bill 123, signed October 2024, allows up to three ADUs per lot in the RS district [4]
Honolulu	No two-ADU ordinance; seeking repeal	Land Use Ordinance still permits one ADU per zoning lot; Council resolution asks the Legislature to repeal the mandate [3][5]
Kauai	No ADU legislation found	Relies on its existing additional-rental-unit framework; no official "reasonable equivalent" determination located

Maui is the clearest case. The county adopted Bill 78 (2026) in response to Act 39, and it took effect July 8, 2026. It allows up to two accessory dwellings alongside the primary home, standardizes rules that previously varied by island and lot size, and prohibits using the new units as transient vacation rentals, short-term rentals, or bed-and-breakfasts [2]. If you own a residentially zoned Maui lot, the two-unit question is settled and your remaining constraints are the county's development standards.

Hawaii County arrived at a more generous result without framing it as Act 39 compliance. Council Bill 123 was signed by Mayor Roth in October 2024. A Hawaii County Planning Department report describes its effect plainly: it "allows the development of up to 3 accessory dwelling units (ADUs) per lot in the RS zoned district" [4]. Because much of Hawaii Island's residential land sits outside the state urban district, Act 39 would not have reached it anyway; Bill 123 is broader than the state floor in the districts it covers.

Honolulu is the county to watch, and the one most likely to trigger the backstop. Its Land Use Ordinance, as amended by Ordinance 25-2, still provides that "[o]nly one accessory dwelling unit is permitted on a zoning lot," with a carve-out that an otherwise-permitted ohana unit does not count toward that one-unit limit [5]. That is a real nuance, since some Oahu lots can carry an ADU plus an ohana unit, and the county could argue that combination is a "reasonable equivalent." But it is not a two-ADU ordinance. Meanwhile, Resolution 25-271, introduced September 24, 2025, asks that a proposal "to repeal county requirements related to accessory dwelling units on residentially zoned lots" be included in the 2026 Hawaiʻi State Association of Counties legislative package. The resolution argues Act 39 "mandates increased density in residential neighborhoods" without ensuring consistency with the City's General Plan [3]. Inclusion in an HSAC package requires all four county councils to agree, and Act 39 remains on the books.

Kauai is the genuine unknown. A review of county council agendas from January 2025 through July 2026 turned up no ADU ordinance responding to Act 39. Kauai has long allowed a primary dwelling plus an ADU plus additional rental units on some residential lots, and it is widely asserted online that this already satisfies the "reasonable equivalent" standard. We could not locate any official county determination saying so. Treat Kauai as unresolved, and ask the Planning Department directly rather than relying on secondhand claims.

The December 31, 2026 Backstop, and Its Proviso

Here is the operative language, because paraphrases of it tend to oversell. If a county has not adopted or amended zoning ordinances under Act 39 by December 31, 2026, then it "shall not deny any permit application on the basis of exceeding the maximum number of housing units allowed" where the owner of a single-family dwelling on a residentially zoned lot applies to build up to two ADUs, "until the county adopts or amends an ordinance pursuant to this section; provided that a county may deny a permit application on the basis of infrastructure, design, or development standards" [1].

Three things follow.

The override is specific and narrow. The only ground the county loses is the unit count. Setbacks, height, lot coverage, parking, design standards, and infrastructure capacity all survive, and subsection (f) separately preserves denial for insufficient utility infrastructure [1]. On a tight Oahu lot with an aging sewer lateral, losing the unit-cap objection may not change the outcome at all.

It is temporary. The backstop runs only "until the county adopts or amends an ordinance." A county can switch it off at any point by legislating, including after January 1, 2027.

It is self-executing but not self-proving. Nothing in Act 39 creates a permit-shot-clock or a deemed-approved remedy, and subsection (j) confirms no vested rights arise [1]. If a county in default denies your application on unit-count grounds anyway, your remedy is an appeal, not an automatic permit. That is a meaningfully worse position than it sounds.

If you own on Oahu and are considering a second accessory unit, the practical read is this: January 2027 may improve your odds, but it will not hand you an approval, and Honolulu can end the window by passing an ordinance. Anyone selling you a "guaranteed two ADUs in 2027" plan is overstating the statute.

Does Act 39 Override My HOA or Deed Restrictions?

Almost certainly not, and this is the single most common error in circulating summaries of the law.

Act 39 did add a new section to HRS chapter 205 addressing private covenants. It says no private covenant for a residentially zoned lot within an urban district "recorded after the effective date of this Act" may limit the number of ADUs below what the county allows, or limit long-term rental of residential units [1]. Read alone, that sounds like a homeowner's win.

The next subsection settles it: "This section shall not apply to any private covenants recorded before the effective date of this Act" [1]. The effective date is May 28, 2024.

So the covenant provision is purely forward-looking. It stops future subdivisions from writing ADU bans into new CC&Rs. It does nothing to the covenants already recorded against essentially every existing Hawaii subdivision, planned community, and condominium property regime. If your CC&Rs were recorded in 1978, or 2004, or in March 2024, Act 39 leaves them fully enforceable.

For most Hawaii homeowners the association is the binding constraint, not the zoning code, and Act 39 does not touch it. Check your declaration and your design-committee rules before you spend anything on plans. Hawaii is not unusual here: Nevada's AB 396 casita law leaves private covenants standing in the same way. If you want to sanity-check what your lot could physically support before you get into the covenant question, our can I build an ADU walkthrough is a reasonable starting point.

The Parts of Act 39 Nobody Talks About

The ADU mandate got the coverage, but two other pieces of the Act matter to anyone actually pulling permits.

Impact fees. Act 39 amended HRS § 46-143(d) to add an eighth factor in calculating a proportionate share of public facility costs: the square footage of the development. Two provisos follow. Where a developer is converting an existing structure, "the square footage of the existing structure shall be deducted from the total square footage of the development when calculating impact fees." And where the impacted facility is water or sewer, the board of water supply may calculate fees on total fixture count instead of square footage [1]. For a garage or basement conversion, that deduction is worth asking about directly.

Administrative subdivision. Act 39 also amended HRS § 46-4 to vest authority over subdivision, consolidation, and resubdivision applications for fully residentially zoned parcels in the state urban district with the county land-use director or a single designated officer, rather than a board. That path excludes parcels on important agricultural land, wetlands, FEMA floodplains, protected-species habitat, state historic districts, and USGS lava zones 1 and 2, and it does not apply to county SMA powers [1]. This is the "further subdivision" element Honolulu's Council objected to alongside the ADU mandate [3].

What To Do Now

1. Confirm your lot is in the state urban district. Outside it, Act 39 simply does not apply. This is a state land-use classification, separate from county zoning, and your county planning department can confirm it.
2. Confirm your county zoning district qualifies. It must be principally reserved for single-family and two-family detached dwellings. Rural and low-density residential districts are excluded by the statute's own definition [1].
3. Ask whether an SMA or high-hazard designation applies. Coastal SMA jurisdiction and county-designated flood, lava, or fire risk areas are all carved out [1].
4. Ask your county which compliance route it chose. The blanket rule under subsection (b) and the district approach under subsection (c) produce very different answers for an individual lot.
5. Read your CC&Rs before anything else. If your covenants were recorded before May 28, 2024, Act 39 gives you no relief from them [1].
6. On Oahu, track the ordinance calendar. Whether Honolulu legislates before December 31, 2026 decides whether the subsection (g) backstop ever switches on for you.
7. Ask about the impact-fee conversion deduction if you are converting existing square footage rather than building new [1].

Frequently Asked Questions

Is it Act 39 or Act 46? Act 39. S.B. 3202 (2024) was approved May 28, 2024 and published as Act 39, Session Laws of Hawaii 2024 [1]. Act 46 shows up in a fair amount of secondary material, including testimony submitted to county councils. Verify the session-law number before trusting a summary that cites Act 46.

Does Act 39 force my county to approve two ADUs on my lot? No. It requires the county to adopt ordinances allowing at least two ADUs, or the reasonable equivalent, on residentially zoned lots, or alternatively to designate qualifying districts. Even a compliant county keeps its development standards, and can deny permits for insufficient utility infrastructure [1].

What if my county misses the December 31, 2026 deadline? The county cannot deny your application on the basis that up to two ADUs exceed the maximum number of housing units allowed. It can still deny on infrastructure, design, or development standards, and the override lasts only until the county adopts an ordinance [1].

Can my HOA still block an ADU in Hawaii? In most cases, yes. Act 39's covenant provision applies only to private covenants recorded after May 28, 2024 and expressly does not apply to covenants recorded before that date [1]. Nearly all existing Hawaii CC&Rs predate it and remain enforceable.

Can I use an Act 39 ADU as a vacation rental? Act 39 protects long-term rental only. It bars counties from prohibiting use of a dwelling unit as a separately leased long-term rental, "as defined by each county," and says nothing protecting short-term rental [1]. Maui's ordinance expressly prohibits transient vacation rental, short-term rental, and bed-and-breakfast use of the new accessory dwellings [2].

Which counties allow two ADUs today? Maui, under Bill 78 (2026), effective July 8, 2026 [2]. Hawaii County allows up to three ADUs per lot in its RS district under Bill 123, signed in October 2024 [4]. Honolulu still limits lots to one ADU, not counting a separately permitted ohana unit [5]. Kauai has adopted no responsive ordinance we could locate.

References

1. [1] Hawaii State Legislature, "Act 39, Session Laws of Hawaii 2024 (S.B. No. 3202, SD2 HD1 CD1)": https://data.capitol.hawaii.gov/sessions/sessionlaws/Years/SLH2024/SLH2024_Act39.pdf
2. [2] County of Maui, "County news release on the new accessory dwelling ordinance, July 16, 2026": https://www.mauicounty.gov/m/newsflash/Home/Detail/19045
3. [3] Honolulu City Council, "Resolution 25-271, relating to the inclusion of a proposal in the 2026 HSAC legislative package to repeal county requirements related to accessory dwelling units": https://hnldoc.ehawaii.gov/hnldoc/document-download?id=26168
4. [4] County of Hawaii Planning Department, "Background report describing County Council Bill 123 (up to three ADUs per lot in the RS district), September 2025": https://records.hawaiicounty.gov/weblink/1/edoc/152003/PD%20Background%20Report%20-%20Ernest%20and%20Elizabeth%20Young%20(PL-REZ-2025-000087).pdf
5. [5] City and County of Honolulu, "Ordinance 25-2, Land Use Ordinance revision (one accessory dwelling unit per zoning lot)": https://files.amlegal.com/pdffiles/Honolulu/ORD25-002.pdf

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