Sorry, I was looking at the wrong year's Form 1040 for the line numbers. I've corrected my previous post to indicate that line 22 of Form 1040 cannot be reduced below zero by this credit.
"... making the excess estimated pre-payments cheated me out of the savers credit."
That's entirely incorrect. The amount that you have withheld for income taxes or pay in estimated taxes has absolutely no bearing on the amount of Retirement Savings Contributions Credit that is applied to your income tax liability. The credit is applied on Form 1040 line 20 and subtracted from income-tax liability on line 22. Credits for tax withholding and estimated taxes do appear on your tax return until line 25.
It would seem that you have Other taxes on Form 1040 line 23 that is not permitted to be reduced by any nonrefundable credits.
