MA DOR has this to say about the rent deduction if married filing separately:
"Married filing separate taxpayers are limited to a rent
deduction equal to 50% of the rent each pays, not to exceed $1,500 per
return. However, a married couple filing separate may allocate the rent
deduction differently (1) provided the amount taken by each spouse does
not exceed 50% of the rent actually paid by that spouse, and (2)
provided their combined rent deduction does not exceed $3,000.
The
spouse claiming a deduction in excess of $1,500 must attach to his/her
return a statement signed by the other spouse giving consent to the
allocation. The statement must list the name, address, social security
number of the consenting spouse and the amount of rental deduction taken
by that spouse."
It's probably safe to say that TurboTax does not handle this special case.
