26 CFR § 20.6165-1 - Bonds where time to pay tax or deficiency has been extended.
(a) Extensions under sections 6161 and 6163(b) of time to pay tax or deficiency. If an extension of time for payment of tax or deficiency is granted under section 6161 or 6163(b), the district director may, if he deems it necessary, require the executor to furnish a bond for the payment of the amount in respect of which the extension is granted in accordance with the terms of the extension. However, such bond shall not exceed double the amount with respect to which the extension is granted. For other provisions relating to bonds required where extensions of time to pay estate taxes or deficiencies are granted under sections 6161 and 6163(b), see the regulations under section 7101 contained in part 301 of this chapter (Regulations on Procedure and Administration).
(b) Extensions under section 6163 of time to pay estate tax attributable to reversionary or remainder interests. As a prerequisite to the postponement of the payment of the tax attributable to a reversionary or remainder interest as provided in § 20.6163-1, a bond equal to double the amount of the tax and interest for the estimated duration of the precedent interest must be furnished conditioned upon the payment of the tax and interest accrued thereon within six months after the termination of the precedent interest. If after the acceptance of a bond it is determined that the amount of the tax attributable to the reversionary or remainder interest was understated in the bond, a new bond or a supplemental bond may be required, or the tax, to the extent of the understatement, may be collected. The bond must be conditioned upon the principal or surety promptly notifying the district director when the precedent interest terminates and upon the principal or surety notifying the district director during the month of September of each year as to the continuance of the precedent interest, if the duration of the precedent interest is dependent upon the life or lives of any person or persons, or is otherwise indefinite. For other provisions relating to bonds where an extension of time has been granted for paying the tax, see the regulations under section 7101 contained in part 301 of this chapter (Regulations on Procedure and Administration).