Coronavirus stimulus payments have started going out to Americans. They're valued at up to $1,200 per adult and $500 per dependent child and were authorized by the CARES Act to mitigate the financial damage caused by the great lockdown.

If you haven't received your payment yet and want to get it ASAP, you may need to act very quickly to provide the IRS with your updated information. Here's when you need to act -- and how to get what you need.

You may need to provide the IRS with your current bank information

The IRS is sending both paper checks and direct deposit payments. But while direct deposits have started, paper checks won't begin going out until the week of April 20. Just five million checks will be mailed per week, which means it could take five months for everyone waiting for a check to get their stimulus payment.

You don't want to be left without your check until August. You need to make sure the IRS has your correct bank information so they can get your check to you via direct deposit. They'll get that information from your 2018 or 2019 tax return if you filed one and provided your bank details. If you receive Social Security or railroad retirement benefits, the IRS can also send your check to the account on file for those payments.

But if you have outdated bank info on your past returns, or didn't provide your bank details, you'll need to tell the IRS about your current bank account. You'll be able to use the online tool to do that if you don't have direct deposit information on file yet or if your information was inaccurate and resulted in a refund check.

And if you didn't file a return in either 2018 or 2019 and aren't receiving Social Security or railroad retirement benefits, you'll need to provide the IRS with not just your bank details but also with other basic financial information about your income and dependents. Otherwise, you won't get any payment at all, even by mail.

You need to update your bank details before the IRS begins processing your payment, or it will be too late. Since they've begun sending payments already, you really need to act now.

How can you get your details to the IRS?

The IRS has created a simple online website you can use to check the status of your payment and to update your bank information. The same site also allows you to submit the financial info needed to get your check if you didn't file a return in 2018 or 2019.

To find out if there's still time to update your bank info, visit the site and click on the "Get My Payment" option. If your payment shows as pending or processed, you cannot change your bank details any more -- it's too late. If it doesn't, you have the option to provide your updated info if things have changed since your last tax return was filed.

If you haven't filed a return at all and don't get Social Security or railroad retirement benefits, visit the same site but click on "Non-Filers: Enter Payment Info Here." Provide information on your dependents and your income to prove eligibility for the coronavirus stimulus to allow the IRS to determine the amount you're owed and to tell them where to send your money.

Don't wait to act

If the IRS sends your check to the wrong bank account, the bank will reject the money if the account is closed. The IRS will be notified and mail a paper check, but this means it will take a lot more time to get your money. If the account is still open but you can't access it for some reason, you'll have to contact the bank to figure out what your options are.

And if the IRS doesn't have your bank details, they'll mail your money to your last known address. But it could take months until they get around to sending it.

To make sure you don't get stuck waiting for your money, make sure the IRS has the information they need to get it to you quickly. Visit the IRS site today to check your payment status and update your data while there's still time.