Millions of Americans have not filed their income taxes with just one month left in the tax filing season, according to the US Internal Revenue Service (IRS), an issue that some experts blame on President Donald Trump’s political rhetoric.

The IRS has received 5.7 million fewer individual tax returns as of February 17 compared to the same period last year, an 8.5-percent drop.

The annual deadline to file one's individual income tax return is April 15.

Experts believe that the trend can largely be blamed on Trump’s immigration policies, which have targeted millions of undocumented immigrants.

According to a report by Bloomberg, with the Trump administration’s promise to crack down on immigration, “undocumented immigrants may be afraid to create a paper trail with the government by claiming tax refunds.”

John Hewitt, chairman and chief executive of Liberty Tax, said earlier this month that there has been less individual taxpayer identification numbers (ITINs) filed this year.

The ITINs are generally used by undocumented immigrants instead of Social Security numbers.

They’re “probably fearful of the Trump initiatives,” Hewitt said in a call with analysts on March 8.

Trump’s promise to introduce major tax cuts, coupled with the Republican plans to replace the Affordable Care Act, or ObamaCare, have also been cited as other reasons.

Meanwhile, Sanjay Baskaran, president of online tax preparer TaxAct, argued that the reason is much simpler: Procrastination.

“Customers waiting longer to file their returns is a trend we have observed for the last four years, although it’s more pronounced this year,” he said.

Data by the IRS shows that the closer its gets to the deadline, the more tax returns come in.

Last year, for example, a whopping 12 million tax returns were filed during the week leading to the April 16 deadline.

Delayed refunds due to the federal government’s crackdown on tax fraud is also blamed by some analysts as the reason.