Taxes in Mercer Island
Washington's no state income tax and Mercer Island's roughly 10.1% combined sales tax apply to residents, layered with King County's real, highest-in-Washington effective property tax rate -- which translates to a genuinely large dollar bill given Mercer Island's exceptionally high home values.
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Learn moreNo state personal income tax -- and the fuller picture
Washington has no state personal income tax. As documented in full in bellevue-wa.js, the state's capital gains excise tax (7% on WA-allocated long-term gains up to $1M, 9.9% above per the 2025 SB 5813 amendment) is real, current, legally settled law -- genuinely, directly relevant given Mercer Island's exceptional household affluence (the school district ranks #1 in Washington for income per household among all 295 districts).
Mercer Island's combined sales tax
Mercer Island's combined sales tax rate is estimated at approximately 10.1% -- confirm the current precise rate directly for a specific address.
King County's property tax rate applies to a genuinely large dollar bill
Mercer Island shares King County's countywide average effective property tax rate (~0.83%), the highest of Washington's 39 counties -- but given home values running $2.3M-$2.7M, the actual annual dollar tax bill on a typical Mercer Island home runs considerably higher than on a typical home in Kirkland or Issaquah at the same rate.
Washington's state estate tax
Washington levies its own state estate tax on estates above a statewide exemption threshold, distinct from the federal estate tax -- a real, current, and genuinely significant consideration for Mercer Island's exceptionally high-net-worth resident base.
Key takeaways
- Washington has no state personal income tax, but does levy a real, current capital gains excise tax (7%-9.9%) directly relevant to Mercer Island's exceptional affluence.
- Mercer Island's combined sales tax is estimated at approximately 10.1%.
- King County's ~0.83% property tax rate translates to a genuinely large dollar bill given Mercer Island's high home values.
- Washington's state estate tax is a genuinely significant consideration for Mercer Island's high-net-worth residents.
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