South Carolina IFTA Tax Rate — 2026

How South Carolina IFTA tax is calculated

For every gallon of diesel your truck "burned" inside South Carolina during the quarter, you owe $0.2800 in IFTA tax. The number of taxable gallons isn't the gallons you bought there — it's the miles you drove inside South Carolina divided by your fleet's average miles-per-gallon for the whole quarter.

Your IFTA return then nets that against the South Carolina fuel-tax you already paid at the pump on gallons purchased inside the state. If you ran more South Carolina miles than you bought South Carolina fuel, you owe the difference. If you bought more South Carolina fuel than you ran South Carolina miles, you get a refund or credit.

Common South Carolina IFTA filing questions

• Do I file IFTA in South Carolina if my home base is here? If your IFTA base jurisdiction is South Carolina, you file your quarterly return with the South Carolina Department of Revenue (or equivalent). Your filing covers every IFTA jurisdiction you ran in, not just South Carolina.
• What if I only drove a few miles through South Carolina? Every IFTA mile counts, even if you only crossed the state. Track them on your trip sheet or ELD report — you'll owe (or get refunded) South Carolina's share whether you bought fuel here or not.
• What if South Carolina fuel is cheaper than the IFTA tax? The IFTA rate above is what you owe per gallon "consumed" in South Carolina. The pump price already includes South Carolina's state fuel tax — that's what gets credited on your return. If you bought all your fuel in a low-tax state and drove all your miles in South Carolina, you'll owe the full South Carolina rate on those gallons at filing time.

South Carolina IFTA filing deadlines

IFTA returns are due quarterly across all 48 contiguous U.S. states, including South Carolina:

• Q1 (Jan–Mar): due April 30
• Q2 (Apr–Jun): due July 31
• Q3 (Jul–Sep): due October 31
• Q4 (Oct–Dec): due January 31

Late filings collect penalties even if you owe nothing — some states charge $50 minimum per late return. File on time even if your net due is $0.