If you are eligible for a payment, all you have to do is file a 2007 tax return and the IRS will do the rest.  The IRS will use information on the 2007 tax return filed by the taxpayer to determine eligibility and calculate the amount of the stimulus payments.

Most taxpayers just need to file as usual.  No other action, extra form or call is necessary.  The IRS will update their website to stay current with information and schedules for disbursement. 

In most cases, the payment will equal the amount of tax liability on the tax return, with a maximum amount of $600 for individuals and $1,200 for taxpayers who file a joint return.

Additionally, the law will allow taxpayers who do not have a tax liability (ie low-income workers and those who receive Social Security benefits or veterans' disability compensation or pensions).   The taxpayer will need at least $3,000 of qualifying income.

Recipients of Social Security, certain Railroad Benefits and certain Veterans' benefits should report their 2007 benefits on Line 14a of Form 1040A or Line 20a of Form 1040.  Taxpayers who already have filed but failed to report these benefits can file an amended return by using   Form 1040X. 

Eligible taxpayers who qualify for a payment will receive an additional $300 for each child who qualifies for the child tax credit. 

To accommodate taxpayers who file tax returns later in the year, the IRS will continue sending payments until Dec. 31.  The IRS also cautions taxpayers that if they file their 2007 tax return and then move they should file a change of address card with the US Postal Service.

See the online calculator for an estimate of the amount you will
receive. 

FAQ  

SCAM e-mails and information about scam calls should be forwarded to phishing@irs.gov

(Source: IRS : IR-2008-18)