The $300 and $600 dollar "Economic Stimulus" checks (equivalent to a cupcake a day, "Let Them Eat Cake", Lewis Black) are not the Tax Refund.
It's simple: employers are required to essentially estimate (yes, there is a mathematical formula involved) how much income tax you have to pay based on your earnings. They deduct it from your paycheck and send it off to the government. Some states also have personal income tax.
But because the US tax system is completely screwed up, this amount paid by your employer is always wrong. There are exemptions and deductions and credits and unreported earnings. So each US citizen is required to sit down with a huge set of forms and esoteric and even contradictory instructions and figure out their taxes all over again, or hire a "tax professional" to do so.
Everything is recalculated and you are left with either: my employer didn't collect enough taxes from me and thus I own the government even more money, or, hey guess what, the government took too much money and owes me (here we get to it) a "Tax Refund".
Yippee!! The government took too much money, used it for months and months without me having access to it or even earning interest on it, and now they'll kindly give it back and I'll treat it like an unexpected present, and go out and spend it on luxury items I probably don't even need.
I, personally, haven't had a "Tax Refund" in years, which many would find a bit depressing, but to me means "I manage my income correctly".