(a) In general. If the executor of an estate of a decedent dying after December 31, 1976, makes an election under section 6166 or 6166A (as in effect prior to its repeal by the Economic Recovery Tax Act of 1981) to defer the payment of estate tax, the executor may make an election under section 6324A. An election under section 6324A will cause a lien in favor of the United States to attach to the estate's section 6166 lien property, as defined in paragraph (b)(1) of this section. This lien is in lieu of the bonds required by sections 2204 and 6165 and in lieu of any lien under section 6324 on the same property with respect to the same estate. The value of the property which the district director may require under section 6324A as section 6166 lien property may not exceed the sum of the deferred amount (as defined in paragraph (e)(1) of this section) and the required interest amount (as defined in paragraph (e)(2) of this section). The unpaid portion of the deferred amount (plus any unpaid interest, additional amount, addition to tax, assessable penalty, and cost attributable to the deferred amount) shall be a lien in favor of the United States on the section 6166 lien property. See § 301.6324A-1 of this chapter (Regulations on Procedure and Administration) for provisions relating to the election of and agreement to the special lien for estate tax deferred under section 6166 or 6166A (as in effect prior to its repeal by the Economic Recovery Tax Act of 1981).

(b) Section 6166 lien property—(1) In general. Section 6166 lien property consists of those interests in real and personal property designated in the agreement referred to in section 6324A (c) (see paragraph (b) of § 301.6324A-1 of this chapter). An interest in property may be designated as section 6166 lien property only to the extent such interest can be expected to survive the deferral period (as defined in paragraph (e)(3) of this section). Property designated, however, need not be property included in the decedent's estate.

(2) Maximum value of required property. The fair market value of the property required by the district director to be designated as section 6166 lien property with respect to any estate shall not be greater than the sum of the deferred amount and the required interest amount, as these terms are defined in paragraphs (e) (1) and (2) of this section. However, the parties to the agreement referred to in section 6324A (c) may voluntarily designate property having a fair market value in excess of that sum. The fair market value of the section 6166 lien property shall be determined as of the date prescribed in section 6151(a) (without regard to any extension) for payment of the estate tax. Such value must take into account any encumbrance on the property (such as a mortgage or a lien under section 6324B).

(3) Additional lien property may be required. If, at any time, the unpaid portion of the deferred amount and the required interest amount exceeds the fair market value of the section 6166 lien property, the district director may require the addition of property to the agreement in an amount up to such excess. When additional property is required, the district director shall make notice and demand upon the agent designated in the agreement setting forth the amount of additional property required. Property having the required value (or other security equal to the required value must be added to the agreement within 90 days after notice and demand from the district director. Failure to comply with the demand within the 90-day period shall be treated as an act accelerating payment of installments under section 6166(g) or 6166A(h) (as in effect prior to its repeal by the Economic Recovery Tax Act of 1981).

(4) Partial substitution of bond. See paragraph (c) of § 301.6324A-1 of this chapter for rules relating to the partial substitution of a bond for the lien where the value of property designated as section 6166 lien property is less than the amount of unpaid estate tax plus interest.

(c) Special rules—(1) Period of lien. The lien under section 6324A arises at the earlier of the date—

(i) The executor is discharged from liability under section 2204; or

(ii) Notice of lien is filed in accordance with § 301.6323(f)-1 of this chapter.

(2) Requirement that lien be filed. The lien imposed by section 6324A is not valid against a purchaser (as defined in paragraph (f) of § 301.6323(h)-1), holder of a security interest (as defined in paragraph (a) of § 301.6323(h)-1), mechanic's lienor (as defined in paragraph (b) of § 301.6323(h)-1), or judgment lien creditor (as defined in paragraph (g) of § 301.6323(h)-1) until notice of the lien is filed. Once filed, the notice of lien remains effective without being refiled.

(3) Priorities. Although a notice of lien under section 6324A had been properly filed, that lien is not valid—

(i) To the extent provided in section 6323(b)(6), relating to real property tax and special assessment liens, regardless of whether such liens came into existence before or after the filing of the notice of Federal tax lien;

(ii) In the case of any real property subject to a lien for repair or improvement, as against a mechanic's lienor, whether or not such lien came into existence before or after the notice of tax lien was filed; and

(iii) As against any security interest set forth in section 6323(c)(3), relating to real property construction or improvement financing agreements, regardless whether such security interest came into existence before or after filing of the notice of tax lien.

(d) Release or discharge of lien. For rules relating to release of the lien imposed by section 6324A or discharge of the section 6166 lien property, see section 6325 and § 301.6325-1 of this chapter.

(e) Definitions. For purposes of section 6324A of this section—

(1) Deferred amount. The deferred amount is the aggregate amount of estate tax deferred under section 6166 or 6166A (as in effect prior to its repeal by the Economic Recovery Tax Act of 1981) determined as of the date prescribed by section 6151(a) for payment of the estate tax.

(2) Required interest amount. The required interest amount is the aggregate amount of interest payable over the first four years of the deferral period. For purposes of computing the required interest amount, the interest rate prescribed by section 6621 in effect on the date prescribed by section 6151(a) for payment of the estate tax shall be used for computing the interest for the first four years of the deferral period. The 4-percent interest rate prescribed by section 6601(j) shall apply to the extent provided in that section. For purposes of computing interest during deferral periods beginning after December 31, 1982, interest shall be compounded daily.

(3) Deferral period. The deferral period is the period for which the payment of tax is deferred pursuant to the election under section 6166 or 6166A (as in effect prior to its repeal by the Economic Recovery Tax Act of 1981).

(4) Application of definitions. In the case of a deficiency, a separate deferred amount, required interest amount, and deferral period shall be determined as of the due date of the first installment after the deficiency is prorated to installments under section 6166 or 6166A (as in effect prior to its repeal by the Economic Recovery Tax Act of 1981).