Tariff Adjustment
Variable accessorial charges applied to motor carrier and intermodal linehaul freight rates absorb operating cost fluctuations driven by wholesale and retail diesel fuel price movements. Motor carriers and rail operators calculate the inland fuel surcharge by linking invoice adjustments directly to regional fuel price indexes published on regular weekly cycles. This rate component floats independently of base transport prices, isolating fuel volatility from negotiated carriage agreements.
Calculation Index
Standard carrier tariffs apply a baseline fuel price threshold, known as the peg, above which fuel surcharges activate according to predetermined monetary or percentage increments. An inland fuel surcharge typically incorporates a step table where every fractional change in the national diesel average yields a corresponding percentage increase on the linehaul freight charge or a dedicated per-mile accessorial rate. Discrepancies emerge when shippers and carriers negotiate differing baseline pegs, scale brackets or underlying public index reference points.
Specialized carrier fleets with lower fuel economy often establish steeper rate progression curves within their tariff structures.
Billing Verification
Shippers conduct freight bill audits to verify that invoice surcharges align with the specific index value active during the week of tender. An inland fuel surcharge must be applied strictly to eligible linehaul freight charges, excluding terminal accessorials, detention fees and secondary handling charges. Inconsistent index dates or improperly stacked accessorial percentages produce systematic billing overcharges that require automated freight payment reconciliation tools.