Territory withdrawn from any fire protection district shall continue to be subject to taxation for the payment of the principal of and interest on any indebtedness, whether evidenced by bonds, notes, or other similar evidences of indebtedness created by election outstanding upon the effective date of withdrawal as fully as though the territory had not been withdrawn. For the purpose of discharging the indebtedness and interest thereon and other obligations, the territory shall be considered a part of the district the same as though not withdrawn. All provisions which could have been used to compel the payment by the withdrawn territory of its portion of the indebtedness and interest thereon had the withdrawal not occurred can be used to compel the payment on the part of the withdrawn territory of the portion for which it is liable. Provided, however, by mutual agreement, the entity annexing or withdrawing territory from the district may acquire the capital assets which represent the proceeds of the indebtedness and pay off or assume the indebtedness to the extent otherwise permitted by law and the terms of the underlying obligation.