Many people think that the April 15th deadline for US tax returns means they can't get a tax refund anymore - but this isn't the case. You actually have up to three years to file your tax return and claim any overpaid US tax back.
The US tax filing deadline is the date when tax returns have to be filed to avoid late penalties and interest on any taxes owed.
So if you've worked in the US anytime between 2006 and 2008 you can still get a US tax rebate. Use taxback.com's free tax calculator to find out how much you can still claim.