In mid-2025, Washington adjusted its state estate tax for estates created on or after July 1, 2025. The new version uses a larger, inflation adjusted deduction of $3,000,000 and higher tax rates that start at 10% and fairly quickly rise to 35%. (For context, the previous state estate tax, applicable for the estates of decedents who passed away before July 1, 2025, uses a $2,193,000 deduction and tax rates that ran from 10% to 20%.)
To estimate the Washington state estate tax someone might owe under the new 2025 law’s rules, use the Washington State estate tax calculator shown below. Instructions and additional information appear below the calculator input and outputs.
Taxable Estate: 0.00
Washington Estate Tax: 0.00
Instructions for Washington State Estate Tax Calculator
You need to describe an estate using the roughly half a dozen inputs. And the three things to know are as follows:
First, Washington state subtracts the following items from your taxable estate: Liabilities, spousal transfers, estate administration costs, charitable contributions and then a new “standard” exclusion equal to $3,000,000 starting July 1, 2025 and then some higher, inflation-adjusted amount in later years.
Note: A special qualified family owned business interest deduction also exists and that can amount to another $3,000,000 roughly. But that deduction is very difficult to use and rather problematic.
Second, if you have out of state real estate, the formulas adjust for this. Washington state doesn’t tax its residents on real property held out of state. (Those other states, by the way, might.) But as an example, if someone holds real estate outside Washington state that amounts to 25 percent of the person’s estate? Washington state only taxes the remaining 75 percent.
Third, the actual tax calculation uses a sliding scale which starts at 10 percent and rises to 35 percent.
Some Other Stuff to Know
Some other things helpful to know:
A wrinkle for people who hold real property inside or outside of Washington state: The values you enter for that property in the “Washington state assets” and “Non-Washington state assets” boxes need to be net of any nonrecourse debt like mortgages the decedent isn’t personally liable for. Use the liabilities box to show only the total recourse liabilities.
You ought to consider the calculation results an estimate. They do give you a good sense of the taxes an estate pays.
Finally, these generalizations maybe help. Fewer estates will need to file estate tax returns under the new law due to the higher, inflation-indexed threshold going forward. And the new law’s higher tax brackets don’t really “kick in” until someone’s estate hits $10,000,000 if single or $15,000,000 if married. But at estate sizes larger than these amounts, the new estate tax becomes strikingly large. Affected taxpayers will want to update their estate and business plans. And probably many will want to consider relocating outside of Washington state. (The tipping point is probably about $30 million of net worth.)
Other Resources
More information about and the text of Washington SB 5813 appears here.
To compare the new bill’s tax to the prior one, you can use this earlier version of the calculator.