The property taxes accrued and rent constituting property taxes accrued on each return shall be totaled. This total, up to seven hundred fifty dollars in rent constituting property taxes actually paid or eleven hundred dollars in actual property tax paid, shall be used in determining the property tax credit. The director of revenue shall prescribe regulations providing for allocations where part of a claimant’s homestead is rented to another or used for nondwelling purposes or where a homestead is owned or rented or used as a dwelling for part of a year.