Washington fuel tax
Base rate
$0.5950
Special diesel, per gallon, 4Q2026.
Surcharge
None
Washington levies no surcharge.
Total
$0.5950
Rank 5 of the 47 states with a rate.
Per mile
9.92c
At 6.0 mpg.
Against every other state with a rate
The 47 states that publish a diesel rate run from $0.1900 to $0.9790 a gallon and average $0.3681. Washington is above that average by $0.2269.
What it costs to cross
IFTA charges you for the fuel you BURN in a state, not the fuel you buy there. So a 500-mile pass through Washington at 6.0 mpg consumes 83.3 taxable gallons whether you fuel here or not. Buy nothing in the state and the whole of it lands on your quarterly return.
| Miles run in Washington | Taxable gallons | Owed if you buy no fuel here |
|---|---|---|
| 100 | 16.7 | $9.92 |
| 250 | 41.7 | $24.79 |
| 500 | 83.3 | $49.58 |
| 1,000 | 166.7 | $99.17 |
| 2,500 | 416.7 | $247.92 |
That 500-mile pass costs $49.58 in Washington tax alone. What buying cheap fuel in a low-tax state actually saves you is the difference in the rack price, not the tax: the tax follows the miles and IFTA collects it either way. This is the single most misunderstood line in owner-operator accounting.
Source: IFTA, Inc. Tax Rate Matrix. Special diesel rate for 4Q2026. Rates are reset every quarter. Read 2026-09-15.