If you are in the 33% marginal tax rate bracket, it is very unlikely that you could make a deductible contribution to a Traditional IRA, and that is the only thing that would reduce your tax. Contributions to a ROTH IRA or non-deductible contributions to a Traditional IRA have no effect on your tax.
You should carefully read the limits on IRA deductions in IRS Pub. 590-A at this link:
http://www.irs.gov/pub/irs-pdf/p590a.pdfIf you are able to make a deductible contribution to a Traditional IRA, then the contribution reduces your tax by the amount of the contribution times your marginal tax rate bracket. So a $1,000 contribution would reduce your tax by $330.
