What happens if my mortgage payment is due before my repayment plan is confirmed?

If this is the case, you would pay your lender directly rather than paying the court-appointed trustee. Typically, once protected by Chapter 13, you make payments to your trustee for purposes of disbursement to creditors. However, if the court has not yet confirmed your plan, you would continue to interact with your lender yourself. The amount paid would then be deducted from the amount you would have paid the court-appointed trustee.