Which item can a taxpayer NOT include as a deductible interest on their mortgage if the total loan amount exceeds the home's cost?

The item that a taxpayer cannot include as deductible interest if the total loan amount exceeds the home's cost is the investment property mortgage.

In the context of tax deductions for mortgage interest, the Internal Revenue Service (IRS) places limits on the amount of interest that can be deducted based on the mortgage amount and the cost basis of the property. For a primary residence and a vacation home, taxpayers can generally deduct interest on loans that do not exceed the value of the property, as long as those properties are used for personal purposes.

However, for investment properties, the rules are more stringent. If the amount of the mortgage loan surpasses the actual cost of the investment property, there might be limitations on how much interest can be deducted. The key factor is that the interest must pertain to debt that is used to acquire, build, or substantially improve the property, and any amount exceeding the value of the property does not qualify for interest deductions.

On the other hand, interest on primary residences, home equity loans, and vacation homes typically allows for more straightforward deductions, as they directly relate to properties owned by the taxpayer for personal use, provided they meet the deduction criteria.