Three states add a surcharge, and it is not a rate
Indiana, Kentucky and Virginia charge a per-gallon surcharge on top of the base fuel tax. It looks like a rate, which is why it so often gets added to one — and that single move can hand you a refund you are not owed.
Only three, and not on every fuel
| JurisdictionCode | Gasoline | Diesel | Gasohol | Propane |
|---|---|---|---|---|
| INIndiana | — | — | — | +0.6300 |
| KYKentucky | 0.2500+0.0450 | 0.2200+0.1050 | 0.2500+0.0450 | 0.2500+0.0450 |
| VAVirginia | 0.3260+0.1530 | 0.3360+0.1430 | 0.3260+0.1530 | 0.3260+0.1530 |
Base rate first, surcharge in amber. A dash means no surcharge on that fuel.
Indiana's surcharge applies to propane only — not to diesel, gasoline or gasohol, where the other two states charge one. And Indiana publishes no base propane rate at all: the surcharge of 0.6300 is the entire tax on that fuel. A table that treats a missing base rate as "untaxed here" gets Indiana propane exactly backwards.
Computed on taxable gallons, never on net
The base tax is charged on net taxable gallons — what you burned there minus what you bought there — so it goes negative when you fuelled up more than you drove. The surcharge is charged on taxable gallons, full stop. It never nets against your purchases and it can never come back as a credit.
-
Base tax
net taxable gallons × base rate. May be negative, and a negative here is a legitimate credit.
-
Surcharge
taxable gallons × surcharge rate. Never negative, whatever the base line did.
Adding the surcharge to the rate is worth $94.50 on one state
Take a quarter running at 5.56 MPG with 2,500 miles in Kentucky and 900 gallons bought there. That is 450 taxable gallons against 900 purchased, so net taxable gallons are -450 — a credit position.
Done correctly: the base line is -450 × 0.2200, and the surcharge is 450 × 0.1050 charged separately and never netted. Together, -$51.75.
Done by adding the surcharge to the rate and running the combined figure through the net-gallons formula: -$146.25. That is $94.50 more credit than Kentucky owes — an overstated refund, which is an underpayment with a friendlier name.
This is not hypothetical. An earlier version of this product did exactly that, and it was caught by reading a state's own instructions rather than by any test. See a full quarter where Kentucky is in credit and still owes its surcharge, or the rule in the context of the whole return.
Every figure on this page is computed by the same engine the product runs, using 3Q2026 rates. The comparison is arithmetic, not an estimate of how often the mistake is made.
Three states, four fuels, one rule that inverts
It is the kind of detail that is fine to know once and expensive to forget in quarter three. CabPurser is being built so you do not have to hold it.
Goes to a person, not a drip sequence.