The proportion of mortgage deduction in the special additional deduction of personal income tax: if the mortgage is shared by both husband and wife, both parties will bear half of it, that is, 50% will be deducted; If it is shared by husband and wife, then the proportion of personal income tax deducted from mortgage is 100%.

Legal objectivity:

Interim Measures for Special Additional Deduction of Individual Income Tax

Article 14

If taxpayers or their spouses use individual housing loans from commercial banks or housing accumulation funds alone or jointly to purchase housing for themselves or their spouses in China, the interest expenses incurred in the first housing loan shall be deducted according to the standard quota of 1 000 yuan per month in the year when the loan interest actually occurred, and the maximum deduction period shall not exceed 240 months. Taxpayers can only enjoy a first home loan interest deduction. The term "first home loan" as mentioned in these Measures refers to the housing loan that enjoys the interest rate of the first home loan when buying a house.

Interim Measures for Special Additional Deduction of Individual Income Tax

Article 14

If taxpayers or their spouses use individual housing loans from commercial banks or housing accumulation funds alone or jointly to purchase housing for themselves or their spouses in China, the interest expenses incurred in the first housing loan shall be deducted according to the standard quota of 1 000 yuan per month in the year when the loan interest actually occurred, and the maximum deduction period shall not exceed 240 months. Taxpayers can only enjoy a first home loan interest deduction. The term "first home loan" as mentioned in these Measures refers to the housing loan that enjoys the interest rate of the first home loan when buying a house.