TurboTax will automatically take these rules when calculating your Massachusetts taxes.
From the Massachusetts Department of Revenue: http://www.mass.gov/dor/individuals/filing-and-payment-information/guide-to-personal-income-tax/dedu...
General Rules
A deduction is allowed for rent paid by the taxpayer during the taxable year for a principal residence located in Massachusetts. This deduction is limited to 50% of the rent paid not to exceed a total deduction of $3,000. The deduction must be for rent that the taxpayer paid to a landlord for the rental or lease of taxpayer's principal residence in Massachusetts.
Rent Paid by Third Party on Taxpayer's Behalf:
If the rent is paid by a third party (such as by a parent) who maintains a principal residence elsewhere, no 50% rental deduction is allowed for either party.
Joint Rental of A Unit:
If two or more persons jointly rent a unit, each occupant using it as his or her principal residence is entitled to a deduction based on the amount of rent each person paid.
Example: two unrelated individuals rent a two bedroom apartment for $1,500 per month. Since they split the rent, e.g. each pays half, or $750 per month, each is entitled to the full $3,000 rental deduction ($750 x 12 = $9,000)
