What is a TMK number in Hawaii, and how do you look one up?
TMK stands for Tax Map Key — the unique parcel identifier used by all four Hawaiian counties. Every real estate transaction, permit application, and zoning lookup in Hawaii starts with the TMK. Here's how the system works and the fastest way to find one.
If you’ve ever tried to pull a permit in Hawaii, close a real estate transaction, or look up a property at the county, someone has asked you for the TMK. It’s the first thing on the permit application. It’s how the City’s GIS layers index every parcel. It’s what your title company uses. And it’s the thing most people don’t know how to find quickly.
Here’s how the system works.
What TMK stands for
TMK stands for Tax Map Key — the parcel identification number used by all four Hawaiian counties (Honolulu, Maui, Hawaii, and Kauai). The number is assigned by the county assessor’s office and persists through ownership changes. It doesn’t change when a property sells, when a name changes, or when a lender records a new lien. The TMK is permanent to the parcel, not to the owner.
The format looks like this: 1-2-3-4-5-6-7
Each segment means something:
- 1 — Island/County (1 = Oahu, 2 = Maui, 3 = Hawaii Island, 4 = Kauai, 5 = Molokai, 7 = Lanai)
- 2-3 — Zone and Section (administrative subdivisions within each island)
- 4 — Plat (the recorded subdivision map or plat)
- 5-6 — Parcel and CPR Unit (the specific lot; CPR unit distinguishes condominium property regime units)
In common usage, people often abbreviate to the last four or five segments — “plat 4, parcel 5” — or write it as (1) 2-3-4-005 with the island number in parentheses.
Why the TMK matters for permits and real estate
The Honolulu DPP’s online permit lookup (honolulupermits.com) indexes by TMK. When you’re checking permit history on a parcel before purchase, pulling the TMK is step one.
County zoning maps, property tax records (qPublic), the Bureau of Conveyances (BOC) at the State level, flood zone maps, shoreline setback data, and the City’s GIS all use TMK as the common key. Once you have the TMK, every other lookup becomes straightforward.
It also appears on your property tax bill — usually labeled as “Tax Map Key” or “Map Key” in the assessment header.
How to look up a TMK from an address
Option 1 — IkenaAI property lookup Type any Hawaii address into ai.ikenagroup.com. It pulls the TMK, zoning district, lot area, building footprint, and county permit deep-links for all 384,262 statewide parcels — free, no account required. This is the fastest path.
Option 2 — Honolulu Property Search (Oahu) The City’s real property assessment search at qPublic lets you search by address and returns the full TMK, owner, and assessment data.
Option 3 — Maui, Hawaii, Kauai Each neighbor island has its own tax records portal. Maui uses mauipropertytax.com, Hawaii County uses the Real Property Tax Division search, and Kauai uses kauaipropertytax.com. All of them search by street address and return the TMK.
Option 4 — Bureau of Conveyances If you’re searching by grantor/grantee or need to trace title, the BOC’s online index at boc.hawaii.gov links instruments to TMKs in the search results.
TMK vs. APN
If you’re working with mainland real estate platforms or lenders, you may see “APN” — Assessor’s Parcel Number. APN is the equivalent in most other states. They’re the same concept: a county-assigned number unique to each parcel. Hawaii just calls it a TMK. If a mainland software tool asks for an APN and you’re in Hawaii, enter the TMK.
Common TMK lookup situations
- Buying property: Verify that the TMK on the listing matches the parcel you’re actually buying. Drive-by addresses can pull up the wrong parcel on corner lots.
- Permit history: Use the TMK to check DPP’s permit database for open permits, violations, or legacy work-without-permit flags before closing.
- ADU eligibility: The zoning attached to the TMK determines whether an ohana unit or ADU is permitted. Two adjacent lots in the same neighborhood can be in different zoning districts.
- Shoreline and flood zones: FEMA and state shoreline setback maps index by TMK and GPS coordinate. The IkenaAI lookup returns both.
The number behind the address
In Hawaii, the address is the human-readable label. The TMK is the legal one. Every county record, every permit, every deed, every tax bill — they all hang on the TMK. Once you know how to find it, everything else opens up.
Ikena Design & Build is a Honolulu software studio building AI-native tools for the trades, real estate, and the people who keep everything moving.
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