Updated September 4, 2026. Quick answer: Hawaii taxes estates above a fixed $5,490,000 exemption at marginal rates from 10% up to 20% on the amount over $10,000,000 of net taxable estate, and the state has offered its own spousal portability election since 2012. A $6,490,000 estate, exactly $1,000,000 over the exemption, owes $100,000 in Hawaii estate tax.
2026 exemption: $5,490,000 · Top rate: 20% · Key statute: Haw. Rev. Stat. sec. 236E-6; Haw. Rev. Stat. sec. 236E-8
Filing deadline and extension
Hawaii Form M-6 is due nine months after the date of death, the same as the federal deadline. An automatic six-month extension to file is available, but an extension of time to file does not extend the time to pay, so payment is still due at the nine-month mark and unpaid tax accrues interest at two-thirds of 1% per month from that date regardless of any filing extension.
How Hawaii’s spousal portability actually works
Hawaii’s applicable exclusion amount includes the federal applicable exclusion amount, which under federal law already folds in any unused exclusion from a predeceased spouse, capped at the frozen 2017 level. But the state treats this as its own election, not an automatic inheritance from the federal return: portability can only be elected on a timely filed estate tax return of the predeceased spouse, regardless of whether that estate is otherwise required to file, meaning a Hawaii M-6 must be filed for the first spouse’s estate, even if no Hawaii tax is owed, or the surviving spouse loses the benefit.
A true marginal tax, not a cliff
Hawaii’s schedule is applied to the Hawaii net taxable estate with each bracket taxed only on the increment above the prior threshold: 10% up to $1,000,000; $100,000 plus 11% from $1,000,000 to $2,000,000; continuing at 12%, 13%, and 14% through $2,000,000 to $5,000,000; $600,000 plus 15.7% from $5,000,000 to $10,000,000; and over $10,000,000 the tax is $1,385,000 plus 20% of the amount above that. There is no cliff anywhere in the schedule.
Hawaii does have spousal portability, and it has to be elected.
A $6,490,000 estate, exactly $1,000,000 over the exemption, owes $100,000. The election that lets a surviving spouse use the rest of the $5,490,000 exemption has existed since 2012, but it is claimed on a timely return rather than granted automatically, and it is the kind of thing missed in a year nobody is thinking about tax.
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Non-resident owners of Hawaii property
An out-of-state decedent is pulled into Hawaii's estate tax if their gross estate includes any real property situated in the state or tangible personal property having a situs in the state. Hawaii apportions both the taxable estate and the exemption itself for nonresidents using a fraction of Hawaii-situs property over the federal gross estate, applied to both the taxable base and the $5,490,000 exclusion, so a nonresident does not get the full exemption, only its Hawaii-situs share. A nonresident's estate is exempt from Hawaii's tax entirely if their home state exempts Hawaii residents' property from its own death taxes.
The math on a $6,490,000 estate
Tax owed: $100,000. Gross estate $6,490,000 minus the fixed exemption of $5,490,000 equals a Hawaii net taxable estate of $1,000,000. The first bracket, $1,000,000 or less, is taxed at a flat 10%: 10% times $1,000,000 equals $100,000.
Honest gaps
capitol.hawaii.gov and legiscan.com were unreachable this session, so a Hawaii bill described in secondary sources as a nonresident-exclusion estate tax proposal carried over into the 2026 session could not be independently confirmed and is omitted. HRS 236E-3, the IRC-conformance section, was itself updated again in 2025 as a routine annual conformity update that does not touch the exemption or rate brackets.
Source note. Read from https://files.hawaii.gov/tax/forms/2024/m6ins.pdf; https://files.hawaii.gov/tax/legal/hrs/hrs_236e.pdf on 2026-09-04.
Related: estate tax by state · who actually pays the estate tax · the lifetime gift and estate tax exemption.
Statutory text read at each state's own department of revenue or legislature. General information, not legal or tax advice; exemptions, rates and filing rules change, and a qualified estate or tax professional should confirm the current figures before you rely on them.