King County prices building permits with $2.46 per square foot, then charges plan review at a flat $8,128.00. Enter your project to see the exact math.
Official county schedule
Effective Jan 1, 2026
Verified Nov 4, 2026
Minimum fee
—
Plan review
Separate
$75k addition
$4,226
Permit fee calculator
King County schedule, eff. Jan 1, 2026
$
sq ft
Estimated permit fees$4,225.50
1. Building permit fee 400 sq ft × $2.46$984.00
2. Plan review fee flat$3,109.00
3. Application screening fee flat fee$126.00
4. State building code surcharge fixed$6.50
May also apply (not in the total)
Fees are estimates based on the official schedule linked below. Confirm with the permit office before applying. Separate electrical, plumbing, mechanical, fire, impact, utility and school fees are usually not included unless they are listed. BuildingPermitCost is not a government permit office, and this is not legal advice.
What common projects cost
Kitchen or bath remodel
$25,000 value, remodel 300 sq ft
$2,157.50
$1,229.00 building permit + $796.00 plan review + $126.00 application screening + $6.50 state building code surcharge
Room addition
$75,000 value, addition 400 sq ft
$4,225.50
$984.00 building permit + $3,109.00 plan review + $126.00 application screening + $6.50 state building code surcharge
New single-family home
$350,000 value, new single-family 2,400 sq ft
$14,164.50
$5,904.00 building permit + $8,128.00 plan review + $126.00 application screening + $6.50 state building code surcharge
How King County calculates your permit fee
The county charges a building permit fee using $2.46 per square foot. Plan review is a separate charge: a flat $8,128.00. Electrical, plumbing and mechanical work gets its own permits.
The fee table
New home - custom or basic (permit inspection fee)
$2.46 per square foot.
Addition or conversion to living space, or garage addition
$2.46 per square foot.
Remodel or repair - one structural modification
A flat $1,229.00.
Added to every matching permit
Application screening fee: a flat $126.00 (All projects)
Surcharges
State building code surcharge: $6.50
What counts as project value
Floor area (square feet). Single-family fees are a fixed application review fee by project type plus a permit inspection fee of $2.46 per sq ft (new homes, additions, accessory structures); remodels are priced by number of structural modifications. Construction value is used only for plan re-submittal or revision fees.
Worked example: a $350,000 new home
Building permit fee: 2,400 sq ft × $2.46 = $5,904.00
Plan review fee: flat = $8,128.00
Application screening fee: flat fee = $126.00
State building code surcharge: fixed = $6.50
Total before trade permits: $14,164.50.
Fees people miss
Fee
Amount
Site review - custom new homeWhen: site review required (depends on storm water manual and codes)
$4,639.00 each
Site review - basic critical area or site review (additions, accessory)When: site review required
$2,033.00 each
Fire sprinkler review / inspection - new homeWhen: fire sprinklers installed
$1,119.00 review + $1,997 inspection
Site condition inspection or development monitoringWhen: if required
$726.00 per trip
School impact mitigationWhen: new dwelling units
see Fee Guide 03
Trade permits are separate. Electrical: Issued by the WA State Department of Labor & Industries, not the county. Plumbing: Plumbing and gas piping permits are issued by Seattle-King County Public Health. Mechanical: Mechanical installation only $183 (up to six systems per dwelling unit).
How to apply
Gather your plans and your project's total value and floor area.
Submit to King County Department of Local Services, Permitting Division.
Pay the permit and plan review fees when invoiced.
Questions: 206-296-6600
How King County compares
A $25,000 remodel costs $2,157.50 in King County: about 5.7 times the national median of $380.00, and the 2nd highest of 10 places we cover in Washington (state median $652.06).
A $75,000 addition costs $4,225.50 in King County: about 5.1 times the national median of $820.58, and the highest of 10 places we cover in Washington (state median $1,357.44).
A $350,000 new home costs $14,164.50 in King County: about 4.9 times the national median of $2,918.63, and the highest of 10 places we cover in Washington (state median $3,956.19).
Cities in King County with their own fee schedule on this site: Auburn, Federal Way, Redmond, Seattle. Inside those cities, check whether the city or the county issues your permit.
A $25,000 remodel: $2,157.50. A $75,000 addition: $4,225.50. A $350,000 new single-family: $14,164.50. These include every fee the schedule applies to that project; trade permits are separate.
Is plan review included in the King County permit fee?
No. Plan review is charged separately at a flat $8,128.00.
How does King County determine project value?
Floor area (square feet). Single-family fees are a fixed application review fee by project type plus a permit inspection fee of $2.46 per sq ft (new homes, additions, accessory structures); remodels are priced by number of structural modifications. Construction value is used only for plan re-submittal or revision fees.
Are electrical, plumbing and mechanical permits included?
No. They are separate permits. Electrical: Issued by the WA State Department of Labor & Industries, not the county. Plumbing: Plumbing and gas piping permits are issued by Seattle-King County Public Health. Mechanical: Mechanical installation only $183 (up to six systems per dwelling unit).
When did these King County fees take effect?
The schedule is effective Jan 1, 2026 (“2026 permit fees, Effective January 1 to December 31, 2026 (Ordinance 20021)”). We last checked it against the official source on Nov 4, 2026.
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