936 for extra information about loans taken out on or earlier than October 13, 1987. You can solely deduct home mortgage interest to the extent that the loan proceeds from your own home mortgage are used to purchase, construct, or considerably improve the house securing the loan. The only exception to this limit is for loans taken out on or earlier than October thirteen, 1987; the mortgage proceeds for these loans are treated as having been used to purchase, build, or substantially improve the home. You figure your share of actual property taxes in the following means. Real property taxes …