Washington (CNN) About 80 million people were sent their stimulus payments this week -- but if you weren't one of them, it doesn't mean you won't get the money.

You're one of roughly 60 million people still waiting. About 90% of Americans are eligible for the payments , which phase out for high-income earners, according to an estimate from the Tax Policy Center.

The Internal Revenue Service started by sending money to the people it could reach the fastest . This was anyone who had direct deposit information already on file with the agency because they were due a refund on either their 2018 or 2019 federal tax returns.

Others, like Social Security and Supplemental Security Income recipients , should receive the payments automatically soon, the IRS said this week.

Then, the agency will begin sending paper checks -- with President Donald Trump's signature -- to those who haven't authorized a direct deposit in the past two years. On Wednesday, IRS officials said those checks should start going out next week, according to a Democratic congressional aide. But the agency can only process roughly 5 million checks a week, so it could take months before all of them are sent out.

Here are five reasons why you might not have received your money yet:

1. You didn't get a federal tax refund in 2018 or 2019

Even if you filed your 2018 or 2019 taxes electronically, that doesn't mean the IRS can direct-deposit the money into your bank account. You must have also received a refund in those years via direct deposit to get the money delivered automatically.

The IRS is not using bank account information it may have used to withdraw from your account if you owed money.

2. Your refund went to an old bank account

If you didn't receive a refund in 2019, or haven't filed yet, the IRS will use the bank account information used to send a refund for the 2018 tax year.

Some people told CNN that the money was sent to an account they have since closed and that the bank transferred the money back to the IRS. In that case, the payment will likely come later by a check in the mail.

A new IRS online tool , called Get My Payment, allows you to input new bank account information -- but it's only helpful if the agency doesn't already have an account on file from a 2018 or 2019 tax return and hasn't yet processed your stimulus payment.

Filing a 2019 return now, if you haven't already done so, is the only way to update direct deposit information that the IRS has on file from a 2018 return. Tax Day was moved from the traditional April 15 to July 15 this year to give filers more time.

3. Your refund went to a temporary account set up by a tax preparer

You may not even realize it, but sometimes tax preparers set up a temporary account and that's where your tax refund is deposited first. They take out their fees and then transfer the remaining money into your bank account or a debit card. Sometimes this is in the form of an advanced loan.

It may take longer for you to receive your stimulus money if that's the case. When stimulus payments were sent out in 2008, this glitch affected about 20 million people. But they eventually received the money by a paper check.

Some people who used popular tax preparers like TurboTax and H&R Block and received a refund on a debit card told CNN that the IRS tool could not confirm the status of their payment when they checked this week.

H&R Block said on its website that it is still waiting for answers from the IRS, but that some people who have used its Emerald debit card will see their stimulus money transferred there.

TurboTax said the IRS has the appropriate banking information for all of its filers and that any of its customers who are eligible for a stimulus payment and had their refund transferred to a debit card will receive their payment without delays or fees.

4. You filed a paper return in 2019

Most people file electronically, but some still send in paper returns.

Amid the coronavirus pandemic, the IRS has many employees working remotely and has stopped processing paper returns until its centers are able to reopen.

If you didn't get a refund directly deposited in 2018 and filed a paper return for 2019, you may be waiting for a paper check with your stimulus money.

5. You aren't normally required to file a tax return

There are millions of low-income people who are not normally required to file tax returns that will have to take some action before receiving their stimulus money.

Generally, these are individuals who did not earn more than $12,200 last year or married couples who did not earn more than $24,400.

But they won't have to file a whole new form, as earlier guidance from the IRS suggested. Instead, it created an online tool for non-filers that asks for basic information including names, date of births, and Social Security numbers for the person filing and his or her dependents. They won't have to provide any income information.

The tool allows you to input bank account information for a direct deposit, or an address to receive a paper check.

How to check your status with the IRS:

On Wednesday, the IRS launched an online tool allowing people to check the status of their payment. While many people were pleased to see the money had been transferred to their bank account, others told CNN that they were frustrated to learn their payment status was not available.

Their statuses may be updated overnight, as the tool is updated daily. But otherwise, those people are left without any options but to keep checking. On its website , the IRS explicitly says not to call about the payments.

The agency is moving much more quickly than it did the last time it delivered stimulus payments in 2008 . The coronavirus money was authorized by the $2.2 trillion congressional stimulus package that was signed into law three weeks ago.