The sales tax rate on Mercer Island, Washington is 10.3 percent as of 2026.1Washington Department of Revenue. Local Sales and Use Tax Rates Q1 2026 That rate applies to most retail purchases on the island, whether you live there or are passing through, and it is well above the national population-weighted average of about 7.5 percent. The Department of Revenue location code for Mercer Island is 1719, which is what sellers use when filing returns for sales sourced to the island.
What Makes Up the 10.3 Percent
Three layers stack together to produce the rate on your receipt. The biggest piece is Washington’s state sales tax of 6.5 percent, set by RCW 82.08.020 and collected on virtually every retail sale statewide.2Washington State Legislature. RCW 82.08.020 Tax Imposed Retail Sales Retail Car Rental
Mercer Island also sits inside King County’s local taxing district and Sound Transit’s Regional Transit Authority boundary. The local component adds 2.4 percent for county and city programs, and Sound Transit levies another 1.4 percent to fund regional mass transit, including light rail.3Sound Transit. Regional Tax Information Local and transit together total 3.8 percent, which combines with the state’s 6.5 percent for the 10.3 percent you see at checkout.1Washington Department of Revenue. Local Sales and Use Tax Rates Q1 2026
The Department of Revenue collects all three components in a single remittance from sellers and then distributes the money to the appropriate state, county, and transit accounts.
What Gets Taxed on Mercer Island
Washington casts a wide net. Any physical item you can see, touch, or measure is generally taxable at retail.4Washington Department of Revenue. Retail Sales Tax Clothing, electronics, furniture, appliances, vehicles, and building materials all carry the full 10.3 percent on Mercer Island.
Many services are taxable too. Landscaping, personal fitness training, cleaning, and automotive repair all require sales tax collection.5Washington Department of Revenue. Services Subject to Sales Tax Construction work, whether a full build or a minor home repair, is taxable on both labor and materials.4Washington Department of Revenue. Retail Sales Tax If you hire someone to install, repair, or alter physical property at your Mercer Island home, expect the 10.3 percent on the invoice. Because tax on services is based on where the work is performed, a contractor driving in from elsewhere still charges Mercer Island’s rate.6Washington Department of Revenue. Determine the Location of My Sale
Digital products are taxed the same way as physical goods. Downloaded music, streamed movies, digital subscriptions, and remote-access software all fall within the state’s definition of a taxable retail sale.7Washington Department of Revenue. Digital Products Including Digital GoodsRCW 82.08.020 Tax Imposed Retail Sales Retail Car Rental A Netflix or Spotify subscription sourced to a Mercer Island address carries the local rate.
Because Washington uses destination-based sourcing, an online purchase shipped to your Mercer Island home is taxed at 10.3 percent no matter where the seller is located.6Washington Department of Revenue. Determine the Location of My Sale A couch shipped from Spokane carries the same rate as one bought on the island.
What’s Exempt
A few categories escape sales tax entirely, and they shape day-to-day spending.
Most grocery items are exempt under RCW 82.08.0293. Food and food ingredients sold for home consumption are not taxed, whether fresh, frozen, canned, or dried, as long as they are sold for ingestion and consumed for taste or nutritional value.8Washington State Legislature. RCW 82.08.0293 Exemptions Food and Food Ingredients The exemption does not cover prepared food, soft drinks, bottled water, candy, or dietary supplements, which all remain taxable.
Prescription drugs are also exempt. RCW 82.08.0281 removes sales tax from drugs dispensed pursuant to a prescription, along with prescription devices used for family planning.9Washington State Legislature. RCW 82.08.0281 Exemptions Prescription Drugs Over-the-counter medications do not qualify.
When You Owe Tax the Seller Didn’t Collect
If you buy something for use on Mercer Island and the seller doesn’t charge sales tax, you owe use tax at the same 10.3 percent rate.10Washington Department of Revenue. Use Tax This commonly comes up with out-of-state purchases, private-party sales, and smaller online retailers that haven’t crossed Washington’s collection threshold. You can’t be charged both sales tax and use tax on the same purchase, but one or the other always applies.
Individuals report and pay use tax through the Department of Revenue’s My DOR online portal or by mailing a Consumer Use Tax Return.10Washington Department of Revenue. Use Tax It’s worth building into your budget any time you buy something without seeing Washington sales tax on the receipt. Marketplace facilitators like Amazon, eBay, and Etsy generally collect and remit tax on behalf of their third-party sellers, so most consumer purchases through those platforms already have Mercer Island’s rate applied at checkout.
Deducting Sales Tax on Your Federal Return
Washington has no state income tax, which gives residents a useful option at federal tax time. Taxpayers who itemize on Schedule A can choose to deduct either state income taxes or state and local sales taxes, and since Washington doesn’t impose an income tax, sales tax is the only option.11Internal Revenue Service. Topic No 503 Deductible Taxes
You can calculate the deduction two ways: add up every receipt for the year, or use the IRS optional sales tax tables that estimate your deduction based on income and family size. The tables are usually the easier route, and you can add the actual tax paid on large purchases like a car or boat on top of the table amount. At 10.3 percent, Mercer Island residents accumulate sales tax faster than most Americans, which makes the deduction worth tracking.
For 2026, the state and local tax (SALT) deduction is capped at $40,400 for most filers, or $20,200 for married filing separately. The cap phases down once modified adjusted gross income exceeds $505,000, dropping to $10,000 for high earners who are fully phased out. Many Mercer Island homeowners combining property tax and sales tax will approach the limit, so logging actual sales tax paid on big-ticket items can help you reach it.
Checking the Current Rate
Sales tax rates change more often than most people realize. New transit levies, county ballot measures, or state legislative action can shift the rate by a fraction of a percent with little fanfare. The Department of Revenue maintains a free Tax Rate Lookup Tool where you can search by street address, ZIP+4, or interactive map to find the current rate and location code for any spot in Washington.12Washington Department of Revenue. Sales and Use Tax Rates For Mercer Island, any island address returns location code 1719 and the combined rate. The department publishes updated rate flyers at the start of each quarter, which is a good checkpoint if you’re a business selling into the island.