IFTA without the spreadsheet
Quarterly fuel tax is a distance problem wearing a fuel problem's clothes. Here is where the miles actually go missing.
Most fleets we talk to reconcile IFTA by exporting miles per jurisdiction, exporting fuel purchases, and squaring the two in a spreadsheet the week the return is due. It works, in the sense that the return gets filed. It also quietly under-reports, and under-reporting is the direction that gets you assessed.
Where the miles go#
Jurisdiction miles come from breaking a trip into segments at each state line. Every system that does this has to decide what to do at the boundary itself, and the naive answer — attribute the segment to the state you were in when the ping arrived — loses distance at every crossing.
The size of the loss is small per crossing and relentless in aggregate. On a run we traced end to end:
- Odometer truth: 676 miles
- Segmented total: 633 miles
- What the report showed: 590 miles
That is a 13% shortfall, and none of it looks wrong on any single line.
The three checks worth running#
Compare total jurisdiction miles against odometer miles. They will not match exactly — deadhead, personal conveyance and yard moves all explain gaps — but the difference should be a percent or two, not a tenth.
Look for jurisdictions with fuel but no miles. A fuel purchase in a state your distance report says you never entered is the clearest possible signal that segments are being dropped.
Check your MPG per jurisdiction. If one state's calculated MPG is wildly off the fleet average, the miles for that state are wrong — the fuel almost never is, because it came from a receipt.
What good looks like#
A clean quarter is one where you can answer "how did we get this number?" for any jurisdiction on the return, in under a minute, without opening a spreadsheet. If you cannot, the return is not wrong yet — but you have no way of knowing when it becomes wrong.