Missed an IFTA deadline — or about to? Enter the net IFTA tax you owe, how many months late you are, and your interest rate to see the late-filing penalty, the interest, and what you'll owe in total. The Q2 2026 return (Apr–Jun) is due July 31, 2026.
Estimate only, not tax advice. The $50-or-10% penalty is the IFTA standard; interest and some penalty details vary by base jurisdiction. Default interest of 1%/month is a representative figure — enter your own jurisdiction's rate. Confirm the exact amount on your base state's IFTA return.
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See Pro →A late IFTA return hits you three ways. First, the penalty: $50 or 10% of your net tax due, whichever is greater — a flat floor that stings most when your quarterly tax is small. Second, interest on the tax you owe, charged for every month (or part of a month) until it's paid, separately on the amount owed to each jurisdiction. Third, the part nobody prices in: a delinquent IFTA account can block your registration renewal and, if it drags on, get your IFTA license suspended — which parks the truck. The penalty and interest are usually small next to a day off the road, so the real cost of "I'll file it next week" is downtime risk, not just the fee.
Because the penalty is the greater of $50 or 10%, the flat $50 rules until your net tax passes $500, then the 10% takes over:
| Net IFTA tax due | 10% of tax | Late-filing penalty |
|---|---|---|
| $0 (late zero/refund return) | $0 | $50 |
| $200 | $20 | $50 |
| $500 | $50 | $50 (the crossover) |
| $1,000 | $100 | $100 |
| $2,500 | $250 | $250 |
Interest is added on top of these figures, monthly, until the tax is paid.
| Quarter | Period | Due date |
|---|---|---|
| Q1 | Jan 1 – Mar 31 | Apr 30, 2026 |
| Q2 | Apr 1 – Jun 30 | Jul 31, 2026 (Friday) |
| Q3 | Jul 1 – Sep 30 | Oct 31, 2026 |
| Q4 | Oct 1 – Dec 31 | Feb 1, 2027 (Jan 31 is a Sunday) |
The return is due the last day of the month after the quarter ends; if that's a weekend or holiday it moves to the next business day. Need to run the return itself first? Use the IFTA fuel tax calculator to get your net tax due, then bring that number back here.
IFTA interest is charged on the tax owed to each member jurisdiction, for every month or fraction of a month the payment is late. Under the IFTA Articles of Agreement the base rate is set once a year at 2 percentage points above the IRS underpayment rate and charged at 1/12 of that per month. Some base jurisdictions set their own rate instead — Texas, for example, uses 0.75% per month (9%/year). A working figure of about 1% per month is close enough for planning; drop your own jurisdiction's rate into the calculator for a tighter number. Because a partial month counts as a whole month, filing even a few days late can trigger a full month of interest.
$50 or 10% of the net tax due, whichever is greater. Owe $300 and the penalty is $50 (10% is only $30); owe $1,000 and it's $100. Interest on the unpaid tax is charged on top, every month until you pay.
Yes. The $50 minimum can still apply to a return filed after the deadline even when your net tax is zero or you're owed a refund. IFTA requires an on-time return every quarter — file even a $0 return by the due date.
On the tax owed to each jurisdiction, per month or part-month late. The IFTA base rate is the IRS underpayment rate plus 2 percentage points, charged at 1/12 monthly; some jurisdictions (e.g. Texas at 0.75%/month) set their own. About 1%/month is a good planning default.
July 31, 2026 (a Friday), covering April 1 – June 30, 2026. Miss it and the late penalty plus monthly interest start accruing.
Yes — repeated late filing or payment can get your IFTA license suspended or revoked, and you usually can't renew your registration or IRP plates with a delinquent account. That downtime costs far more than the penalty.
Late-filing penalty = the greater of $50 or 10% of net tax due (IFTA Articles of Agreement, R1220). Interest = net tax owed × monthly rate × months late, where a partial month counts as a whole month; the IFTA base rate is the IRS underpayment rate + 2 percentage points charged at 1/12 per month (R1230), with some jurisdictions setting their own rate. Total late cost = penalty + interest. Deadlines are the last day of the month after each quarter (next business day if a weekend/holiday). Sources: IFTA, Inc., and member jurisdiction guidance (e.g. Texas Comptroller, SCDMV). Last updated July 2026. Estimate for planning only — not tax advice; confirm with your base jurisdiction. Built by TruckMargin.