| The IRS allows 2 unmarried individuals buying a principal residence to be able to claim this First Home Buyer Credit. The taxpayers purchasing a qualified home "may allocate the credit among the individual owners in any reasonable manner. But, the total amount allocated between the owners may not exceed the smaller of $7500 or 10% of the purchase price of the house."
However, you must meet the additional test in that neither your mother-in-law or you must have owned a main home at any time during the three years prior to the date of purchase. If either of you did own a home during that period than neither of you would be eligible for the credit. | 
