Washington Mortgage Calculator (with Washington Property Taxes & Insurance)

Washington is one of only a handful of states with no state income tax, which materially changes how residents should think about the total cost of homeownership compared to income-tax states offering identically priced homes. Washington still funds state and local government through property tax, retail sales tax, and, notably, the Real Estate Excise Tax (REET) charged to sellers at the time of sale, but the absence of income tax on wages tends to leave more take-home pay available for housing costs, which is one reason home prices in the greater Seattle metro area have historically outpaced many comparably sized income-tax states.

This calculator uses a 0.98% effective statewide property tax rate, which is close to the national average and considerably lower than what a buyer would face in a high-property-tax state like Vermont or New Jersey. Combined with a standard 30-year amortization and a flat monthly insurance estimate, the resulting PITI figure reflects a mortgage payment structure similar to what a Washington-licensed lender would present on a Loan Estimate, though buyers in higher-cost King County markets should expect their specific property tax bill to reflect a higher assessed home value even at a similar millage rate.

1. Down payment and loan principal. Home Price times the down payment percentage gives the cash down; the remainder becomes the loan principal. At $380,000 with 20% down, that is $76,000 down and $304,000 financed.
2. Principal and interest. The loan principal amortizes over 360 monthly periods (30 years) using the standard mortgage payment formula, PMT = P x [r(1+r)^n] / [(1+r)^n - 1], where r is the monthly rate (annual APR / 12).
3. Property tax. Home Price times 0.98% gives the estimated annual property tax, divided by 12 for the monthly escrow contribution.
4. Insurance. A flat $125 monthly estimate represents typical homeowners insurance, added to complete the PITI total.

Using the platform's verified baseline: a $380,000 home, 20% down, and a 6.5% fixed rate.

• Home price: $380,000.00
• Down payment (20%): $76,000.00
• Loan principal: $304,000.00
• Monthly rate: 6.5% / 12 = 0.54167%
• Principal and interest (verified): $1,921.48
• Estimated monthly property tax (0.98% annual / 12): $310.33
• Estimated monthly insurance: $125.00
• Estimated total monthly PITI: approximately $2,356.82
• Total interest paid over 30 years: roughly $387,735

Buyers running the built-in higher-price scenario, which models a 25% increase to $475,000, will see both the principal and interest payment and the monthly property tax line scale upward together, since property tax here is calculated as a percentage of home value rather than a fixed dollar figure.

• Real Estate Excise Tax (REET). Washington charges sellers a graduated excise tax, generally ranging from about 1.1% to 3% of the sale price depending on value tier, at closing. This is a seller-side, one-time closing cost, not part of the ongoing monthly PITI this calculator models.
• King County and metro-area assessment premiums. The 0.98% figure is a statewide effective average; homes in high-demand Seattle-area neighborhoods often carry higher assessed values relative to comparable homes elsewhere in the state, which raises the actual tax bill even at a similar rate.
• Private mortgage insurance (PMI). Down payments below 20% typically require PMI, which is not included in this calculator's output.
• Local levies and special voter-approved measures. Washington school districts and municipalities frequently pass local property tax levies for schools, parks, and infrastructure that can push an individual property's effective rate above the statewide average used here.
• Earthquake insurance. Given Washington's seismic risk, particularly in the Puget Sound region, many homeowners carry a separate earthquake policy that is not included in the flat $125 monthly insurance estimate.

• Forgetting the Real Estate Excise Tax when planning a future sale. While irrelevant to this calculator's monthly payment output, sellers in Washington should budget for REET as a significant closing cost that this mortgage calculator does not project.
• Assuming no state income tax means no state tax burden at all. Washington offsets the absence of income tax with comparatively higher reliance on sales tax and property tax levies, so total tax burden should be evaluated holistically rather than assuming Washington is uniformly low-tax.
• Underestimating PMI on the 5% down payment scenario. That built-in scenario substantially raises the loan principal; an actual 5% down transaction would typically also carry a PMI premium not reflected in this tool's output.
• Overlooking local voter-approved levies stacking on top of the base rate. Washington's frequent local levy elections mean the effective property tax rate on a specific home can run above the 0.98% statewide average used in this calculator.
• Not budgeting separately for earthquake coverage. The flat insurance estimate here reflects standard homeowners coverage; Washington's seismic risk profile makes a separate earthquake policy a common additional cost many buyers overlook until they get a full insurance quote.

• Washington State Department of Revenue, property tax statistics and Real Estate Excise Tax guidance.
• Washington State Department of Revenue, county assessor and levy rate resources.
• Consumer Financial Protection Bureau (CFPB), Regulation Z and mortgage disclosure standards.
• Tax Foundation, State and Local Property Tax Rankings and State Tax Comparisons.