What is an ADU under Hawaiʻi law?

An ADU is a secondary dwelling permitted on the same parcel as a primary residence. It is accessory in use and may be detached or attached, subject to zoning and building rules.

How many ADUs are allowed on one Big Island property?

Hawaiʻi County rules may allow up to three ADUs on a single lot, depending on zoning, lot size, and infrastructure capacity.

Can ADUs use catchment water?

Yes. Hawaiʻi County now clearly allows ADUs to be served by compliant rainwater catchment systems.

Do ADUs require a separate septic system?

Not necessarily. State Act 224 allows one septic or aerobic system to serve up to five bedrooms total across all dwellings.

Does Act 224 allow cesspools?

No. The law applies only to approved septic or aerobic wastewater systems, not cesspools.

Is the 1,250 sq. ft. ADU size guaranteed?

No. The 1,250 square foot limit is a state maximum. Actual ADU size depends on county zoning and site conditions.

Do CC&Rs override County ADU rules?

Yes. Private covenants and subdivision restrictions may prohibit or limit ADUs even if county rules allow them.

Are these ADU rules already in effect?

Yes. Both Hawaiʻi County Bill 123 and State Act 224 are currently in effect.

Can ADUs be used as long-term rentals?

In many cases, yes. Long-term residential use is generally allowed where zoning permits, though short-term rental rules are separate.

Does zoning still matter with the new laws?

Yes. Zoning remains the primary factor in determining what may be built. The new laws expand flexibility but do not replace zoning rules.

Main Content

Home » News and Updates » Page 2

News and Updates

Big Island ADU Laws 2024: What Hawaiʻi County and State Rules Now Allow

By Emil Knysh and Kai IohKai and Emil are luxury real estate advisors based in Kona, Hawai‘i, specializing in resort and ultra-high-net-worth markets across the Big Island. Executive Summary This page explains how 2024 updates to Ha...

January 6, 2026

Hawai‘i County Long-Term Rental Tax Class Explained: What Big Island Property Owners Need to Know

By Kai Ioh | Nov 2025 Executive Summary This page explains Hawai‘i County’s new Long-Term Rental (LTR) property tax classification for Big Island homes. It is relevant for property owners, investors, and landlords renting h...

January 1, 2026

Gentleman's farm was used to offset real property tax in Hawiaii. The tax system will change in 2026.

How Hawai‘i County Assesses Real Property Taxes: What Every Property Owner Should Know and New Changes (2025 update)

By Kai Ioh and KE Team Hawaii. Kai Ioh is a luxury real estate advisor based in Kona, Hawai‘i, specializing in resort and ultra-high-net-worth markets across the Big Island. Key Takeaways Hawai‘i County uses a mass appraisal system, not individual appraisals, to assess over 141,000 parcels each year. Assessed values reflect market conditions as of January […]

December 22, 2025

Maui’s Bill 9 Explained: What Hawaii’s New Vacation Rental Law Means for the Big Island and Beyond

Kai Ioh | December 2025 Maui County just took a decisive step that every Hawaii property owner should be paying attention to. Earlier this month, Mayor Richard Bissen signed Bill 9 into law, following final approval by the Maui County Cou...

December 18, 2025

New Big Island STVR Law (Bill 47): What Homeowners Need to Know

Kai and Emil | Updated Dec 21, 2025 Hawaii County has taken a decisive step in reshaping the rules for short-term vacation rentals (STVRs). With Bill 47 signed into law on June 23, 2025, homeowners across the Big Island need to prepare for a...

December 10, 2025

What a 50-Year Mortgage Could Mean for Hawai‘i Buyers & Investors

50-Year Mortgages: What Hawai‘i Buyers & Investors Need to Know Emil Knysh | Dec 2025 A practical and balanced breakdown for first-time buyers, second-home owners, and investors. As affordability continues to challenge homebuyers...

December 2, 2025

When Kona Becomes the Center of the (Ironman) Universe

It’s that time of year again, when the normally laid-back town of Kailua-Kona transforms into a global stage of grit, glory, and Spandex/Lycra. While I’ve been preoccupied riding the emotional rollercoaster of the Dodgers’ postseason (ca...

October 9, 2025

Compass Is About to Become the World’s Largest Brokerage: What This Pending Merger Means for You

Kai and Emil | September 2025 Big things are on the horizon, and if you’re a client, friend, or follower of Compass, you’ll want to pay attention. Compass recently announced its plan to acquire Anywhere Real Estate in an all-stock deal. T...

September 30, 2025

Hawaii Insurance Crisis: September 2025 Update

By Kai Ioh | September 2025 September Update: Programs Making a Difference On September 9, Sue Savio, one of Hawaii’s most respected insurance experts, shared something we haven’t heard often during this crisis: real optimism. According...

September 16, 2025

Hawaii Condo Insurance Crisis: New Law Brings Relief—But Not a Miracle Cure

By Kai Ioh | July 2025 Not Our First Rodeo: An Ongoing Crisis If you’ve followed my updates—starting in August 2024 and again in early 2025—you know Hawaii’s condo insurance crisis didn’t arrive overnight. Since last summer, we�...

July 19, 2025

« Previous 1 2 3 4 5 Next »