President Donald Trump signed the Coronavirus Aid, Relief, and Economic Security Act, or CARES Act, into law on March 27.

The $2 trillion stimulus package, the largest emergency relief bill in American history, will direct one-time payments, or "recovery rebates," of up to $1,200 to many Americans.

You do not have to sign up to receive a stimulus check. The process is automatic for most Americans who qualify.

Here's how to get a stimulus check:

1. Have a Social Security number

To get a stimulus check, you need to have a Social Security number. Nonresident aliens, people without a Social Security number, and adult dependents are not eligible.

2. File a tax return for 2018 or 2019

The size of your stimulus check is based on the adjusted gross income listed on the latest tax return you filed, either this year's tax return or 2018's.

Americans whose adjusted gross income was less than $75,000 will receive the maximum amount: $1,200. Reduced payments are sent to single filers who earned between $75,000 and $99,000, or married filers who earned between $150,000 and $198,000. There's also a $500 payment per child under age 17 for parents in the payment.

Business Insider's Andy Kiersz created the following chart showing how much taxpayers will receive from the stimulus package based on filing status and income.

Not everyone has to file, however. The IRS will be sending automatic payments of $1,200 each to Social Security recipients and railroad retirees using the payment method for their regular benefits, whether direct deposit or a home address.

People who receive Supplemental Security Income (SSI) and Veterans Affairs (VA) beneficiaries will also get their payments automatically and don't need to file a tax return.

3. Use the IRS' free online tool to speed up payment

If you don't have a tax-filing obligation and don't receive federal benefits, the IRS urges you to use its new tool for non-filers so you can provide payment information and receive your money quickly.

The tool, which can be found here, asks for direct-deposit details (if available), Social Security number, mailing address, date of birth, and number of qualifying children in order to create and submit a simple tax return (Form 1040).

TurboTax has a free portal of its own for those who are not required to file a full tax return this year and want to submit direct-deposit details to the IRS. It has the same requirements as the IRS tool.

4. Provide updated bank information to the IRS

If you didn't provide bank information on your 2019 tax return — maybe because you didn't receive a refund — you can use the "Get My Payment" tool on the IRS website to set up direct deposit.

Note that the tool won't work if you haven't filed a return for 2019. If your latest return filed is for 2018 and doesn't have direct-deposit info, you'll get a paper check in the mail unless you file your 2019 return.

5. Wait for direct deposit or a paper check

Direct-deposit payments started going out April 13 and will continue throughout the month. Paper checks start going out the week of April 20. Read here to find out when your stimulus payment is coming.

Once the IRS has delivered your payment, either by direct deposit or mail, you should receive a notice within 15 days at your last known address confirming how and when the money was sent to you.

This post was updated on April 17, 2020 to include new information from the IRS.