If you are referring to the MA state tax deduction for mandatory contributions to the MA pension system shown in Box 14Y on your W-2, it should be picked up if you enter it on your W-2 Box 14, and choose MA State or US Retirement System in the drop-down box. It will then display properly on MA Form 1, Line 11, to a maximum deduction of $2000.
If, as @SteamTrain, indicates, it is for the Retirement Savings Contribution Credit, it is irrelevant.
