(1) If property qualifying for the credit is owned by a husband and wife, the credit may be applied to their joint tax liability if filing a joint tax return.

(2) If husband and wife file separately, and the property is jointly held, the credit must be computed individually by each spouse and applied to the corresponding tax liabilities.

(3) When filing separately, one spouse's credit cannot be applied to the other spouse's tax liability.

(4) Carryovers of unused preservation credit may only be applied to the tax liability of the spouse who is entitled to claim the credit. If in a carryover year husband and wife who previously filed separately, now file a joint return, carryover credits must be applied separately to each spouse's share of the joint tax liability.