Look on Form 8606, Line 14 of your 2011 tax return to get the total IRA basis from prior years. If your 2011 tax return did not have a Form 8606, then find the Form 8606 from your 2010 tax return to get the total IRA basis from prior years. If you don't have a prior year Form 8606 or your prior year Form 8606 is inaccurate, calculate your IRA basis from prior years by adding up all of the IRA contributions you have made over the years, then subtracting the IRA deductions you have taken on your tax returns over the years. The difference is the total amount of nondeductible IRA contributions you have made in prior years and is your total IRA basis.