I am guessing OP was able to decrease his/her taxes owed by $1500 (e.g. by deducting marginal income by $3000 at a combined state and federal marginal tax rate of ~50%).

*Edit: or, as cbhl points out below, OP is married filing separately, in which case the deduction limit is $1500/year (multiplied by marginal tax rate to yield actual tax savings).