It depends on who paid the expense.  You live in Pennsylvania, a separate property state, which means that you should allocate any deductions to the spouse who paid them and is responsible to pay them.  (Community property states have a different set of rules, but PA is not a community property state).  The allocation you use has to be consistent according to who paid the amounts and who is responsible to do so.  If both paid a portion, each can claim the portion that they paid.  This IRS website explains this in more detail:  Married Filing Separate splitting Itemized Deductions

If one spouse itemizes deductions, the other spouse must also itemize.