Impact Fees

Click here for current Impact Fee Rates.

Impact fees are authorized by Chapter 82.02 of the Revised Code of Washington (RCW) and imposed on new development to help pay for public infrastructure required to accommodate the new development. The funds collected must be expended or encumbered for their intended purpose within 10 years.

School and Park Impact Fees were adopted by the Mercer Island City Council in 2015. The School Impact Fees went into effect in 2015 and the Park Impact Fees went into effect in 2016. City Council adopted Transportation Impact Fees in 2016.  School and Park Impact Fees are assessed only on new residential dwellings. 

Impact fees are not assessed on:

• Replacement residences (when an existing legal dwelling is demolished and replaced with a new residential unit)
• Remodeling or reconstruction of existing dwellings
• Accessory Dwelling Units (ADU's)
• Temporary, transitional, senior and affordable housing (exempt from school impact fees only)
• Non-residential accessory structures, such as sheds or garages

School Impact Fees

Pursuant to Ordinance No. 20C-24, Mercer Island School District (MISD) is not collecting impact fees at this time. MISD may revisit school impact fees at a later date as enrollment projections are updated in the future.

Park Impact Fees

Pursuant to MICC 19.18, Mercer Island collects impact fees for parks. Fees are used to address the impact from new development on park facilities including publicly owned parks, open space and recreational facilities. For more information on park impact fees, please see the 2022 Parks Impact Fee Rate Study.

Transportation Impact Fees

Pursuant to MICC 19.19, Mercer Island collects impact fees for transportation. Fees are used to address the impact from new development on transportation facilities such as public streets and roads, and ensure an adequate level of service, consistent with the capital facilities plan of the City of Mercer Island Comprehensive Plan. For more information of transportation impact fees, please see the 2022 Transportation Impact Fees Rate Study.

Impact Fee Rates

Click here to view 2024 Impact Fee rates.  Impact fee rates are updated annually.

Fee Payment

As required by State law (RCW 82.02), impact fees are charged at the issuance of a project’s building permit. Payment is due before the building permit can be issued, but applicants may request deferred payment for residential impact fees. Impact fees can be deferred until (1) final inspection; (2) issuance of the Certificate of Occupancy or equivalent certification; or (3) the closing of the first sale of the property after the issuance of the applicable building permit, whichever comes first; provided that the term of the impact fee deferral shall not exceed 18 months from the date of building permit issuance.

Requesting Deferred Payment

Requesting an impact fee deferral requires applicants to sign a deferred payment lien and pay applicable fees, including an administration fee. The lien will be recorded against the property, to be released upon payment of the impact fee. See the link below for further information.