Q4 2026 IFTA diesel rate
Washington IFTA fuel tax rate, Q4 2026
WAWashington · diesel$0.5950/gal
Unchanged from Q3 2026.
Checked 2026-10-14 against dol.wa.gov, Washington's own published rate.
Calculate Washington for Q4 2026Free. No account.
What you owe Washington
IFTA apportions your fuel by miles. Divide total miles by total gallons for fleet MPG, turn your Washington miles into taxable gallons, subtract the tax-paid gallons you bought in Washington, and multiply by $0.5950.
Example: 1,000 miles in Washington at 6.5 MPG is 153.85 taxable gallons. With 100 tax-paid gallons bought there, 53.85 × $0.5950 = $32.04 owed to Washington.
This rate is for diesel, Q4 2026. You still file with your base jurisdiction; keep your trip records and receipts.