Seattle Impact Fees and What Builders Pay Instead

People budgeting a Seattle project often go looking for the city's impact fee schedule. There is not one. Seattle does not charge a transportation impact fee and it does not charge a school impact fee, which makes it unusual among Washington cities of its size.

Seattle still collects money from new development through other channels, and the largest of those charges can run past what an impact fee would cost.

What an impact fee is

A 2018 presentation to the City Council's Sustainability and Transportation Committee defines transportation impact fees as one time charges paid by new development, authorized by the 1990 Growth Management Act, that fund improvements adding capacity to the transportation network. It says the fees can only pay for facilities serving new growth, that the money must be used within 10 years on public streets and roads, and that eligible projects must appear in the capital facilities element of a comprehensive plan. Most urban jurisdictions in Washington have one.

Seattle has studied the idea for years without adopting it. The City Council adopted the One Seattle Plan on December 16, 2025, and it took effect on January 21, 2026. The adopted plan still frames impact fees as an option rather than a program. Transportation policy T 10.8 reads "Consider use of transportation impact fees to help fund transportation system improvements needed to serve growth."

Chapter 22.900 of the Seattle Municipal Code lists everything the Department of Construction and Inspections charges for development, and it contains no transportation impact fee and no school impact fee. The 2018 presentation calls impact fees an alternative to SEPA mitigation for system improvements. Transportation conditions on a large project come out of environmental review instead, one project at a time.

Mandatory Housing Affordability

The biggest development charge in Seattle is Mandatory Housing Affordability, usually shortened to MHA. SDCI Tip 257 names the two governing chapters. Chapter 23.58B is titled the Affordable Housing Impact Mitigation Program for Commercial Development, and Chapter 23.58C covers residential and live work development.

MHA applies to property after the City Council approves a rezone that raises the height limit or the floor area ratio. Most rezoned areas carry an MHA suffix of M, M1, or M2, though some zones are subject without one. The commercial requirement starts above 4,000 square feet of gross floor area in commercial use, and the residential requirement applies to any project that adds units, including alterations.

There are two ways to comply. The performance option means building affordable units inside the project. The payment option means paying the city, and those payments fund low income housing.

For the residential payment option under Section 23.58C.040, take the total gross floor area in residential and live work use, subtract underground residential parking, and multiply by the payment amount per square foot for the zone. SDCI's illustration takes 50,000 gross square feet, subtracts 10,000 of underground parking, and multiplies the remaining 40,000 by an example rate of $20 per square foot for an $800,000 payment. For the performance option under Section 23.58C.050, multiply the total number of units by a percentage set for the zone. SDCI's example takes 36 units at 9 percent for 3.24 units, so the developer provides 4 affordable units or provides 3 and pays for the fraction.

The rate depends on the zone, the MHA suffix, and whether the site sits in a low, medium, or high MHA area. Rates adjust each year for the consumer price index, effective March 1. In the table that took effect on March 1, 2026, residential payment amounts run from $8.47 to $50.46 per square foot and commercial payment amounts run from $7.87 to $32.66 per square foot. The highest residential rate is close to six times the lowest.

SDCI expects the contribution documented on the plans before it issues a master use permit or a building permit, and says recorded agreements and any payments may also be required before the building permit is issued. Applications with an affordable housing contribution also pay $550 to the Office of Housing for its review.

SDCI permit fees

Permit fees scale with construction value rather than unit count. The permit fee and the plan review fee both come off the same valuation table, so a building reviewed against drawings pays twice the table figure plus a technology fee of 5 percent. The tables and three worked examples are in how much a Seattle building permit costs.

Utility connection charges

Seattle Public Utilities began charging System Development Charges on January 1, 2026, with an updated charge for water, a new charge for wastewater, and a new charge for drainage when a project increases hard surface. The wastewater and drainage charges apply only inside the city.

The published charge menu prices these by meter size. On a street that is not an arterial, a 2 inch domestic service carries an installation fee of $8,975, a water system development charge of $36,570, and a sewer system development charge of $13,780, for $59,325 before the drainage charge. A three quarter inch service on the same street totals $14,300, and installation for services of 4 inches and larger is quoted site by site.

King County charges separately for sewer treatment capacity. The 2026 capacity charge is $77.99 per residential customer equivalent per month for properties connecting on or after January 1, 2026, billed for 15 years unless the balance is paid off early. Buildings with five or more units count 0.63 equivalents per unit, so a 100 unit building counts 63 equivalents, which is $4,913.37 a month. Non residential space is converted at 20 plumbing fixtures per equivalent.

Work in the right of way adds Seattle Department of Transportation charges. For a basic tap on an arterial, the utility charge menu estimates an SDOT total of $1,768, covering the street use permit fee, the arterial fee, an inspection fee, and a traffic control plan.

How the structure compares

An impact fee city gives you a published rate per unit or per square foot, tied to a project list, that you can look up on day one and that is collected at building permit issuance. MHA matches that in two respects, since it is also a published rate per square foot collected before the permit issues.

MHA money funds affordable housing rather than roads, schools, parks, or fire stations. MHA can also be satisfied by building units instead of paying, which no impact fee allows. The rest of Seattle's charges track physical connections rather than growth, so utility charges follow meter size and hard surface while permit fees follow construction value. You cannot price a Seattle project from one table.

Frequently asked questions

Does Seattle charge impact fees? No. Seattle has no transportation impact fee and no school impact fee. Adopting one would require separate legislation setting a rate schedule.

Is MHA an impact fee? Not in the legal sense. It comes out of the land use code as a condition of rezoned development capacity rather than the Growth Management Act impact fee authority, and it can be met by providing units.

Do I pay a school impact fee in Seattle? No. Seattle does not levy one.

What is the largest single charge on a typical mid rise project? For a rezoned site, MHA usually is. Multiply your chargeable floor area by the rate for your zone and compare that against the permit fees. In a high MHA area the housing payment normally runs several times larger.

Tracking real projects

MHA obligations follow the zone, and the zone follows the site. BuildVue tracks every Seattle project with its address, permit stage, and construction value. Browse them on the map, and read our guide to the master use permit for the stage where MHA gets documented first.