As the Iran war continues, and traffic through the Strait of Hormuz, a key global oil shipping route, remains stalled, many Americans are seeing higher gas prices.

That elevated cost threatens to offset larger tax refunds this season, depending on how long the Iran conflict lasts, some experts say.

Iran on Wednesday received President Donald Trump’s 15-point plan to end the war, which initially lowered crude oil prices. But that drop reversed on Thursday after the country rejected the U.S. ceasefire offer.

Meanwhile, American consumers are still paying higher prices at the pump. The price of gasoline on Thursday was at a nationwide average of $3.98 a gallon, up by roughly 33% from one month ago, according to AAA.

Those higher gas prices could chip away at the windfall received by some taxpayers this spring. As of Mar. 13, the average refund amount for individual filers was $3,623, about $350 more than a year earlier, according to the latest IRS data.