The last two digits of your Social Security number, and whether or not you opt for direct deposit, will determine how quickly you receive your tax rebate check from the IRS.

The payments are to start going out May 2 and be completed by mid-July for people whose income tax returns are processed by the April 15 deadline. Roughly 25 percent of all payments will be made in the first three weeks, the Internal Revenue Service said.

Filers who choose direct deposit for their regular refund get their rebates first. Paper rebate checks don't begin going out until May 16.

People who are not due a regular tax refund still can get their rebate checks direct-deposited by filling out the direct deposit lines on their returns.

The timeline for the rebates covers tax returns "processed" by April 15. That means your best shot at getting your money as soon as possible is to file electronically at least a week before the filing deadline and to have any refund direct-deposited into your account.

The first batch of rebate payments will go to those who file electronically and whose Social Security numbers end in 00 to 20. The last batch goes to paper filers with Social Security numbers ending in 88 to 99.

On a jointly filed return, the timing is based on the first Social Security number listed.

People who file their returns late can expect to receive their rebates about two weeks after receiving their tax refunds, but not before they would have received their payment if they had filed on time.

Rebates won't be issued for returns filed after Oct. 15.

The majority of households are to receive the maximum $600 for singles, $1,200 for couples filing jointly and $300 per child as part of the federal economic stimulus package aimed at boosting the ailing economy.

People who don't earn enough money to pay any federal income taxes, but make at least $3,000 -- including people whose only income is from Social Security or veterans' disability payments -- can qualify for the minimum $300 rebate for individuals and $600 per married couple.

The catch is anyone who wants a rebate must file a 2007 tax return to get their money, even if they aren't normally required to file one.

The rebates do not affect the amount of any regular tax refund and are not taxable by the state of Pennsylvania.

For more information, visit www.irs.gov and click the "Rebate questions?" link.

For low-income and elderly taxpayers, free tax-preparation assistance is available through the Volunteer Income Tax Assistance program (call 1-800-906-9887 to locate the nearest VITA site) and through an AARP Tax Aide site (1-888-227-7669).

In addition, three area IRS taxpayer assistance centers will be open this Saturday from 9 a.m. to 3 p.m. to help people who don't normally file income tax returns file for their rebate payments. The offices are at 1000 Liberty Ave., Downtown (412-395-5667); 4314 Old William Penn Highway, Monroeville (412-856-1913); and 162 W. Chestnut St., Washington, Pa. (724-229-5985).