Seattle business tax certificates, permits and tree service registration

Washington licenses contractors at the state level, and Seattle adds its own business tax certificate, its own B&O tax, a tree service registry, a permit office and a noise ordinance. This page uses the City Finance, Seattle Department of Construction and Inspections (SDCI) and Seattle Public Utilities pages as read in October 2026. It is general information, not legal or tax advice. Confirm the details with the office named before you act.

Washington registers contractors, Seattle taxes and permits them

Under the state layer, Labor and Industries (L&I) registers every construction contractor, requires a bond and liability insurance, and runs workers' comp. Our Washington contractor licenses guide and the Washington start-up page cover it. Seattle's own rules come in four parts: the business license tax certificate from City Finance, the Seattle B&O tax, permits and inspections from SDCI, and local ordinances on noise, trees and drainage. SDCI's tree registry shows how the layers connect: it requires a current Seattle business license and a state contractor registration under chapter 18.27 RCW before it will list a tree company.

The Seattle business license tax certificate

City Finance says most businesses operating in Seattle need a business license tax certificate, home-based businesses included, and that businesses based outside the city need one if they do business within it. Only the owner needs one, not employees. The 2026 annual fee depends on prior-year taxable revenue:

A new applicant pays the first tier for the first year, or half of it when the business starts on or after July 1. Certificates expire December 31. Renewals paid by December 31 or in January carry no penalty; February adds $10 and March 1 onward adds $20. You apply or renew online through FileLocal, and renewals cannot be made by phone. There is a 2026 exemption for a business with $4,000 or less of annual gross income in the city and no place of business there, and it does not cover regulatory licenses or specialized permits. City Finance asks you to get a state Unified Business Identifier first when your business is required to have one, which in practice ties this step to your Washington business license.

B&O tax: the 2026 change that matters to a small crew

Seattle's Business and Occupation tax is a gross receipts tax, separate from the state's B&O tax. City Finance's Seattle Shield page says that beginning January 1, 2026 the taxable threshold rose from $100,000 to $2 million, and taxpayers above it take a $2 million standard deduction. Two details catch people. A business under the threshold owes no tax but still has to file a return reporting $0 due. Some quarterly filers were told in early 2026 that they would switch to annual returns; the 2026 annual return is due April 30, 2027. Returns go in through FileLocal; ask License and Tax Administration for the current mailing address if you file on paper. The page does not list the new rates by class, so read them on City Finance's rates page rather than from a third-party site.

Tree service companies must register with SDCI

If you remove trees or prune big limbs, Seattle has a registry you need to know about first. SDCI requires providers doing commercial tree work for pay on private property to be registered. Reportable work means removing live branches 4 inches in diameter or larger, pruning or removing live roots 2 inches or larger, removing live branches that make up 25 percent or more of a tree's foliage-bearing area, or removing any Tier 1 to 4 tree. SDCI says pruning fruit-production trees and maintaining hedges is not reportable. Its page does not address stump grinding, so ask SDCI at sdci-trees@seattle.gov before assuming a stump job is outside the registry.

To register you need a Seattle Services Portal account, a current Seattle business license, a Washington contractor registration (not required for consulting-only registrations), a certificate of insurance with at least $1,000,000 of commercial general liability naming the City as additional insured, and at least one ISA certified arborist, employed or on retainer. Registration lasts a year. Commercial vehicles must show the registration number, business name and a phone number or email on the sides and rear in letters at least 2 inches tall. Before reportable work the provider posts a public notice on SDCI's site at least 3 full business days ahead, or 6 full business days ahead to remove a tree 6 inches DSH or larger. The on-site posting stays up while the work runs and for five days after; SDCI's page describes that last part as encouraged in one place and required in another, so leave it up. A provider that breaks the tree code can be removed from the registry for one year. Our landscaping start-up guide covers the wider business.

When SDCI wants a permit and when it does not

SDCI's Do You Need a Permit page says minor repairs or alterations costing $6,000 or less in any six-month period usually need no permit, and that the figure is fair market value of labor and parts, even if you do the work yourself. Work that usually needs no permit, outside environmentally critical areas, includes painting or cleaning a building, kitchen cabinets, insulating existing buildings, slab patios, fences under 8 feet high with no concrete or masonry elements above 6 feet, some retaining walls no taller than 4 feet and replacing roof sheathing on detached one- and two-family houses to match the existing structure. Work on load-bearing supports or changes to the building envelope needs a permit no matter how small, as does work that reduces egress, light, ventilation or fire resistance.

Re-roofing has its own page. For one- and two-family homes and townhouses, SDCI says no re-roof permit is needed when the building envelope is unchanged apart from adding or replacing insulation, and insulation-only work needs no permit if the new insulation is equal to or better than the existing. For commercial and multifamily buildings, a re-roof permit is needed to repair more than 500 square feet or replace roof cover, sheathing or insulation. No on-site inspection is required; you close the permit by emailing an Affidavit-Roof Replacement to the inspections office. SDCI's page on building without a permit says it may issue a stop work order and fine you up to $500 per day.

Construction hours and wash water

SDCI's noise code page lists construction hours of 7 a.m. to 10 p.m. on weekdays and 9 a.m. to 10 p.m. on weekends and legal holidays. In lowrise, midrise, highrise, residential-commercial and neighborhood commercial zones the cutoff is 7 p.m. Impact equipment such as jackhammers and pile drivers runs 8 a.m. to 5 p.m. on weekdays and 9 a.m. to 5 p.m. on weekends and holidays. Seattle's legal holidays for this purpose are New Year's Day, Memorial Day, Independence Day, Labor Day, Thanksgiving, the day after Thanksgiving and Christmas Day. Work outside the hours needs a noise variance.

For pressure washing, Seattle Public Utilities' pollution control program works with businesses on pollution prevention, but we found no Seattle page written for mobile washers. Ask Seattle Public Utilities how to handle your wash water before you take jobs on sloped lots or near drains, and read our pressure washing start-up guide for general practice.

A wet season and a short dry one

NOAA's 1991 to 2020 normals for Seattle-Tacoma airport show 39.34 inches of precipitation a year, 6.3 inches of snow and a 53.7 degree annual average. The monthly split sets the calendar: July averages 0.60 inches and August 0.97, while November averages 6.31, December 5.72 and January 5.78. Exterior painting, deck staining and roof work cluster in the dry summer. Moss, gutters and drainage fill the rest of the year.

Where Seattle's numbers belong on your site and phones

Put your state contractor registration number and your Seattle business license on your website, and for tree work add the SDCI registration number that must also appear on your trucks. Washington requires consent from everyone on a recorded call (RCW 9.73.030), so an AI receptionist that answers Seattle calls should announce the recording at the start of the call. Our call recording guide shows how.

Frequently asked questions