Washington’s New Property Tax Law Makes Now the Best Time to Build an ADU in King or Pierce County
If you’ve been considering building an Accessory Dwelling Unit (ADU) in your backyard or converting a garage into a rental, there’s important news you should know. In May 2025, Washington state Governor Bob Ferguson signed Engrossed Senate Bill 5529 into law, creating a major opportunity for homeowners in King County and Pierce County.
The new legislation expands upon previous legislation that excludes newly built ADUs from being added to your property’s tax value, making it easier and more affordable to invest in your home. Previously only available to King County homeowners, this new bill expands the tax exemptions to Pierce County as well.
At S&E Remodeling, we help homeowners throughout Western Washington build code-compliant ADUs. Whether you’re looking to convert your garage, design a basement apartment, or construct a backyard cottage, our team is here to guide you through every step of the process.
What Is an ADU?
An Accessory Dwelling Unit, also known as a granny flat, in-law suite, or detached ADU, is a small residential unit built on the same lot as a single-family home. ADUs are ideal for:
- Generating rental income,
- Accommodating multi-generational living,
- Housing aging parents or caregivers,
- Creating flexible space for a home office or studio.
About the New Law: ESB 5529
Engrossed Senate Bill 5529 provides a property tax exemption for new ADUs built in counties with populations greater than 900,000; this includes King County and Pierce County. With this change, homeowners can add an ADU without having it raise the assessed value of their property for tax purposes.
This tax incentive was created to encourage the construction of ADUs and to help alleviate Washington’s ongoing housing shortage.
Why You Should Consider Building Now
This law creates a unique opportunity for homeowners to build an ADU in King County or Pierce County with long-term financial benefits. Here’s why now is the right time:
- You can save significantly on property taxes,
- You can increase your usable living space and your home’s market value,
- You can create a steady stream of passive rental income,
- You can provide essential housing options in your community.
Local zoning laws have already become more ADU-friendly in many areas throughout Western Washington; with this new tax exemption in place, the advantages are even greater.
Your Local ADU Builder in King and Pierce County
S&E Remodeling is your trusted ADU builder in Pierce County and King County. We manage every aspect of the project, including planning, permitting, construction, and inspection. Our team ensures that every ADU meets local codes and reflects your unique vision and goals.
We specialize in building ADUs, DADUs, in-law suites, garage conversions, studios, and more.
Take Advantage of the New ADU Property Tax Exemption
If you are a homeowner in King County or Pierce County, now is the perfect time to explore the benefits of building an ADU. With no increase in your property tax value, you can expand your living space or create a valuable rental unit without the financial burden that once came with it.
We are proud to be a top-rated ADU contractor in Western Washington, offering free consultations to help you get started. Call us today or fill out our contact form to schedule your initial consultation.