The recent sharp increases in the cost of fuel are having an effect on the fuel tax refunds some carriers can get in some states for the use of motor fuel off the highway.

The American Trucking Associations' State Laws Newsletter explains that many states offer a refund for fuel used in reefer units, and some also for fuel used in power take-offs (such as for unloading bulk commodities) and (in a few states) for idling off the highway. States often make it difficult for carriers to obtain those refunds, and one way states do that is to impose their sales tax on the fuel they've just exempted from fuel tax.
Highway fuel is sales tax exempt in most states, but once it's declared to have been used for another purpose, the fuel becomes taxable. This has always served to reduce carriers' refunds in some states, but now, with the price of diesel so high, the sales tax on the fuel often exceeds the fuel tax refund altogether.