If only part of the mortgage is repaid in advance, it will naturally not affect the subsequent tax deduction. After all, the mortgage is still being paid.

In the year when the loan interest actually occurs, it is generally deducted according to the standard of 1000 per month (the maximum deduction period is no more than 240 months).

Of course, if you pay off the mortgage in advance, you can't deduct the tax. Even if you apply for a new mortgage later, you can't deduct it. After all, the special additional deduction of housing loan interest is limited to the interest of the first housing loan.