Still waiting for your tax refund? You’re going to have to be patient.

It’s been almost four months since the filing deadline for your taxes, and you haven’t gotten your refund check yet.

Should you be worried? Not necessarily.

What should you do? Probably nothing.

What can you do? Probably nothing.

Are you alone? Absolutely not. According to the Internal Revenue Service, as of Sept. 4, there were still 8.5 million returns waiting to be processed.

The IRS has been working through a backlog of returns that need manual review. As of mid-June, it had received 152,465,000 returns and processed 141,032,000 of them. More than 104 million filers were issued refunds totaling almost $285.5 billion.

But you’re wondering where your refund is and what happened to your return. Which, of course, you filed on or before May 17.

Returns are opened in the order they’re received. So if you didn’t get yours in until that May 17 deadline, you’re at the back of the line.

According to the IRS, it has been “opening mail within normal time frames,” and all the returns it received either electronically or by mail before April have already been processed “if the return had no errors or did not require further review.”

That’s one possible holdup. You might have made a mistake on your return. In many instances, even if you have — like errors in the Earned Income Tax Credit or the Additional Child Tax Credit — the IRS doesn’t need to contact you, but mistakes “do require special handling by an IRS employee.” And that could delay your refund by “more than 21 days … and in some cases this work could take 90 to 120 days.”

Yikes. That’s 3-4 months.

And if the IRS needs more information from you, you’ll get a letter. In the mail. Another added delay.

If you don’t get a letter asking for more info, chances are there’s nothing more you need to do. Or can do. Except wait.

The more returns that need correcting, the longer it’s going to take. And the IRS “is having to correct significantly more errors on tax returns than in previous years.” As of May 1, there were 9.8 million returns that need to be corrected, the most ever in a single year. That number was down to 780,000 by Sept. 4.

You can check Where’s My Refund? to find the status of your return. It will tell you if the IRS has received your return and whether it is being processed or reviewed.

Whatever you do, “don’t file a second tax return,” the IRS advises. That would really cause you some problems.