WASHINGTON, April 28 (UPI) -- The first $50 billion worth of U.S. economic stimulus checks should in mailboxes by the end of May, government officials said.

The first 7.4 million checks are expected to be in the mail by May 9 and another 130 million checks should be in the mail by the end of the summer, CNNMoney.com reported Monday.

Single tax filers with $75,000 and joint filers with under $150,000 in adjusted gross incomes will be eligible for checks, as will 20 million senior citizens living on Social Security and 250,000 disabled veterans, the report said.

Single filers could receive as much as $600, while joint filers could find a check worth $1,200 in their mailboxes.

Parents will also find a bonus of $300 per child under 17 with no cap set on the number of children per family.

And, the tax rebate is tax-free. Filers in 2009 won't have to report the tax rebate as income for 2008, the report said.