Sales Tax in Mercer Island, Washington in 2025

We'll walk you through how the sales tax rate is determined for Mercer Island and address some common questions you may have. We'll also cover how to collect, audit, and remit sales tax in Mercer Island.

Plus, we’ll share the best solution that will ensure you are always compliant across the entire sales tax lifecycle.

Disclaimer: Our sales tax data is updated on a quarterly basis.

Mercer Island Sales Tax Rate 2025

Mercer Island is located in King County in Washington, United States, and has a sales tax rate of 10.20%. This includes local and state sales tax rates.

Here is the breakdown of the Mercer Island's sales tax:

Tax Jurisdiction	Sales Tax Rate
State Tax	6.50%
County Tax	1.40%
Special Tax	2.30%
Combined Rate	10.20%

This rate applies to the following zip codes in Mercer Island:

98004, 98040, 98118, 98006, 98039, 98056

How Does the Mercer Island Sales Tax Compare to the Rest of Washington?

Mercer Island’s 10.20% sales tax rate is among some of the highest sales tax rates in Washington. It is only 0.40% lower than Washington’s highest rate, which is 10.60% in places like Mukilteo.

Mercer Island’s rate is 2.70% higher than Washington’s lowest sales tax, which stands at 7.50% in places like Goldendale.

To give you a better idea, here’s a comparison of Mercer Island sales tax rates with a few other cities in Washington:

.

City	Sales Tax Rates
Goldendale	7.50%
Morton	7.80%
Mesa	8.10%
Omak	8.50%
Woodinville	8.80%-10.20%
Gold Bar	9.10%
Mercer Island	10.20%
Mukilteo	10.60%

You can also compare the sales tax rate of Mercer Island against the Washington cities closest in population size:

• Tumwater's sales tax rate is 9.70%
• Moses Lake's sales tax rate is 8.50%

What Creates Sales Tax Nexus in Mercer Island?

Mercer Island has the same nexus rules as mentioned in the Washington state tax law. It doesn’t have any separate sales tax nexus rules.

Read More: Check out this detailed guide on Sales Tax in Washington.

Any of the following conditions can create a  Washington sales tax nexus in  Mercer Island: 

• Economic Nexus: Out-of-state businesses with taxable sales of more than $100,000 in the past 12 months.

• Physical Location: Businesses with a store, office, warehouse, inventory held by a marketplace facilitator, or other places of business. Distributing taxable items using mediums other than mail or common carriers also creates a nexus.

• Employee Location: Businesses with employees or third-party representatives in the state. This also applies if the employees are engaged in soliciting sales, providing services like product training, constructing, installing, or maintaining real or tangible personal property in Washington,

• Events: Businesses that participate in more than one trade convention per year or make retail sales at any trade convention must register for sales tax. However, if the trade convention is marketed to the general public, it becomes a trade show, and participating businesses should apply for a sales tax permit.    

What Products Are Exempt from Mercer Island Sales Tax?

Sales tax exemptions for Mercer Island are granted by the Washington sales tax law. As a result, some items that enjoy sales tax exemption in Mercer Island are:

• Farm products, such as horticultural services, feed, seed, and poultry.
• Producer goods, like manufacturing machinery used for production, semiconductor materials, and computers.
• Public activities, such as road construction, ridesharing vehicles, and fuel for urban transit.
• Health-related purchases, like prescription drugs, medical devices, and blood banks.

Who Needs a Sales Permit in Mercer Island?

The state usually grants a sales permit or business license in the United States. 

So, you should register with the Department of Revenue if you fulfill any of these conditions:

• Your business needs to collect retail sales tax.
• You need city, county, or state endorsements.
• You plan to hire employees in the next 90 days.
• Your gross income is $12,000 per year or more.
• Your business is required to pay any other taxes or fees to the Department of Revenue.
• Your business requires city, county, and state endorsements.
• You are an out-of-state business that meets the sales tax nexus in Washington.

How to Collect Sales Tax in Mercer Island

Washington is a destination-based sales tax collection state. This means when you sell to a customer in Washington, you should charge the sales tax rate at the buyer’s ship-to address. 

For instance, whether your business is in Los Angeles, California or Tumwater, Washington, if you sell to a buyer in Mercer Island, Washington — you should charge the sales tax in Mercer Island.

Learn more about origin-based and destination-based sales tax sourcing here.

How to File and Pay Sales Tax in Mercer Island

There are two options to file and pay Mercer Island sales tax returns:

• File and pay online: Pay through Washington MyDOR. All Washington monthly and quarterly sales tax filers are required to file and pay online.
• File and pay by mail: Businesses with waivers should file by mail. You can get your return forms at the Washington Department of Revenue website.
• Or, you can streamline your sales tax collection with Zamp. 

This way, you can leverage our accurate calculations and easy, one-click registrations to maintain compliance across the United States.