Tax season kicks off next week, and the IRS is warning that things are going to be pretty messy this year.

In December, the IRS still had 6 million unprocessed individual returns from last year, creating a backlog that could cause even more delays.

Larry Gray, a certified public accountant in southern Missouri, said some of his clients still haven’t received their tax refunds from last year.

“And the sad thing is that anytime we slow down the refunds, that impacts the taxpayer and their family,” Gray said.

The delay affects not just their finances, but their ability to file accurately this year. For the IRS, a backlog will make processing returns harder for years to come.

“This does have the potential to snowball,” said Garrett Watson, senior policy analyst at the Tax Foundation.

Many of last year’s delays involved paper returns, he said. Mail deliveries were slow and staffing shortages meant there were fewer people to open all those envelopes and enter data into computers. Plus, with the rollout of COVID relief programs came changes to the tax code.

“So not only has the IRS dealt with these pandemic disruptions, but they’ve also had to turn on a dime to administer important forms of support like the stimulus payments or the expanded child tax credit,” he said.

That didn’t just bring changes for the IRS but for taxpayers too, who had lots of questions. The IRS received a record number of calls last year — more than 280 million. It was only able to answer about 10% of them.

This year, taxes will include another round of stimulus checks and changes to the child tax credit.

“That’s also going to provoke a lot of questions taxpayers have, so I would anticipate that this is going to be another year of record numbers of phone calls coming in to the IRS,” said Janet Holtzblatt, senior fellow with the Urban-Brookings Tax Policy Center.

This year, Holtzblatt advised that people file early and electronically — and have a bit of patience.

“Patience is a virtue when it comes to the IRS, but not all of us can afford patience when expecting refunds,” she said.

The National Retail Federation’s Tax Returns Data Center said that last year, most consumers planned to put their refunds into savings, pay for everyday expenses or pay off debt.