The Internal Revenue Service is far behind on processing returns and refunds for 2019 and 2020 taxes, and a staffing shortage is compounding the problem.

The Wall Street Journal reports the IRS is currently reviewing roughly 16 million 2020 returns, because of tax changes in 2020 and in March. Another 1.3 million from the previous year are still being processed. And with 15% fewer employees than a decade ago, the agency is struggling to handle the flood of questions. Call volume has doubled, sometimes hitting as many as 1,500 calls per second.

And the problems don’t look like they’ll be resolved soon.

Beyond handling normal returns, the IRS is overseeing stimulus payments and child tax credits, due to begin this summer. Changes to how unemployment benefits are taxed are also forcing it to reexamine millions of early filings already received.

Officials suggest whether you’re waiting on a refund or a stimulus check, the best information source for citizens is the “Where’s My Refund?” tool. Updates only occur weekly, though. Calling the IRS for information about either will most likely result in a long wait and no additional information.

The good news: If your refund is issued after April 15, the IRS will pay you interest on that money (assuming you filed before the May 17 deadline). The rate works out to roughly 3% annually.

The bad news: That interest is considered taxable income on your 2021 return.