Only two problems with that idea...

--There's no assurance that the public would actually buy things that would create demand, production and more jobs. They didn't with the 2008 tax rebate money, they saved most of it. If they used a lot of it to save or pay down debt, no stimulus would occur. Basically, too much risk that the public wouldn't do what would actually stimulate the economy--spend on goods.

--The second reason is actually the basis for why the public may not spend on the right things discussed above. A temporary tax reduction violates a tried-and-true economic theory for which Milton Friedman won a Nobel Prize. Friedman, who was a reknown expert in consumption theory, proved that consumption patterns would not change substantially unless consumers had the confidence that their income levels would be relatively permanent. From a theoretical perspective--well proven but yet theoretical--a six month vacation from income taxes would not be expected to result in consumption changes that would be beneficial in stimulating the economy in the long term.