In general. Section 6166 allows an executor to elect to extend payment of part or all of the portion of the estate tax which is attributable to a closely held business interest (as defined in section 6166(b)(1)). If it is made at the time the estate tax return is filed, the election is applicable both to the tax originally determined to be due and to certain deficiencies. If no election is made when the estate tax return is filed, up to the full amount of certain later deficiencies (but not any tax originally determined to be due) may be paid in installments.

Time and manner of election. The election provided under section 6166(a) is made by attaching to a timely filed estate tax return a notice of election containing the following information:

The decedent's name and taxpayer identification number as they appear on the estate tax return;

The amount of tax which is to be paid in installments;

The date selected for payment of the first installment;

The number of annual installments, including the first installment, in which the tax is to be paid;

The properties shown on the estate tax return which constitute the closely held business interest (identified by schedule and item number); and

The facts which formed the basis for the executor's conclusion that the estate qualifies for payment of the estate tax in installments.

Treatment of certain deficiencies—(1) No election before assessment of deficiency. Where a deficiency is assessed and no election, including a protective election, has been made under section 6166(a) to pay any tax in installments, the executor may elect under section 6166(h) to pay the portion of the deficiency attributable to the closely held business interest in installments. However, this is true only if the estate qualifies under section 6166 based upon values as finally determined (or agreed to following examination of a return). Such an election is exercised by filing a notice of election with the Internal Revenue Service office where the estate tax return was filed. The notice of election must be filed within 60 days after issuance of notice and demand for payment of the deficiency, and it must contain the same information as is required under paragraph (b) of this section. The notice of election is to be accompanied by payment of the amount of tax and interest, the date for payment of which has arrived as determined under paragraphs (e) and (f) of this section, plus any amount of unpaid tax and interest which is not attributable to the closely held business interest and which is not eligible for further extension (or currently extended) under another section (other than section 6166A).

Election made with estate tax return. If the executor makes an election under section 6166(a) (other than a protective election) at the time the estate tax return is filed and a deficiency is later assessed, the portion of the deficiency which is attributable to the closely held business interest (but not any accrued interest thereon) will be prorated to the installments payable pursuant to the original section 6166(a) election. Any part of the deficiency prorated to an installment, the date for payment of which has arrived, is due upon notice and demand. Interest for any such period, including the deferral period, is payable upon notice and demand.

Portion of deficiency attributable to closely held business interest. Only that portion of any deficiency which is attributable to a closely held business interest may be paid in installments under section 6166. The amount of any deficiency which is so attributable is the difference between the amount of tax which the executor has previously elected to pay in installments under section 6166 and the maximum amount of tax which the executor could have elected to pay in installments on the basis of a return which reflects the adjustments that resulted in the deficiency.

Protective election. A protective election may be made to defer payment of any portion of tax remaining unpaid at the time values are finally determined (or agreed to following examination of a return) and any deficiencies attributable to the closely held business interest (within the meaning of paragraph (c)(3) of this section). Extension of tax payments pursuant to this election is contingent upon final values meeting the requirements of section 6166. A protective election does not, however, extend the time for payment of any amount of tax. Rules for such extensions are contained in sections 6161, 6163, and 6166A. A protective election is made by filing a notice of election with a timely filed estate tax return stating that the election is being made. Within 60 days after values are finally determined (or agreed to following examination of a return), a final notice of election which sets forth the information required under paragraph (b) of this section must be filed with the Internal Revenue Service office where the original estate tax return was filed. That notice of final election is to be accompanied by payment of any amount of previously unpaid tax and interest, the date for payment of which has arrived as determined under paragraphs (e) and (f) of this section, plus any amount of unpaid tax and interest which is not attributable to the closely held business interest and which is not eligible for further extension (or currently extended) under another section (other than section 6166A).

Special rules—(1) Effect of deficiencies and protective elections upon payment. Upon election to extend the time for payment of a deficiency or upon final determination of values following a protective election, the executor must prorate the tax or deficiency attributable to the closely held business interest among all installments. All amounts attributed to installments which would have been due had the election been made at the time the tax was due to be paid under section 6151(a) and all accrued interest must be paid at the time the election is made.

Determination of date for payment of first installment. The executor may defer payment of tax (but not interest) for any period up to 5 years from the date determined under section 6151(a) for payment of the estate tax. The date chosen for payment of the first installment of tax is not required to be on an annual anniversary of the original due date of the tax; however, it must be the date within any month which corresponds to the day of the month determined under section 6151(a).

Rule for computing interest. Section 6601(j) provides a special 4 percent interest rate for the amount of tax (including deficiencies) which is to be paid in installments under section 6166. This special interest rate applies only to that amount of tax which is to be paid in installments and which does not exceed the limitation of section 6601(j)(2). Where payment of a greater amount of tax than is subject to section 6601(j)(2) is extended under section 6166, each installment is deemed to be comprised of both tax subject to the 4 percent interest rate and tax subject to the rate otherwise prescribed by section 6621. The percentage of any installment subject to the special 4 percent rate is equal to the percentage of the total tax payable in installments which is subject to the 4 percent rate. Where an election is made under the provisions of paragraphs (b) or (c) (1) of this section, the 4 percent rate applies from the date on which the estate tax was originally due to be paid. If only a protective election is made, section 6601(j) applies to the amount which is to be paid in installments, limited to the amount of any deficiency, from the due date for payment of estate tax. After the date upon which the section 6166 election is made final, section 6601(j) applies to the entire amount to be paid in installments.

Relation of sections 6166 and 6166A. No election may be made under section 6166 if an election under section 6166A applies with respect to an estate. For example, no election can be made under section 6166(h) where an executor has made an election under section 6166A. If an election is timely made under either section 6166 or section 6166A, however, a protective election can be made under the other section at the same time. If the executor then files a timely notice of final election under the section protectively elected and pays any amounts determined to be due currently following final determination of (or agreement as to) estate tax values, the original election under the other provision will be deemed never to have applied to the estate.

Special rule for estates for which elections under section 6166 are made on or before August 30, 1980. An election to extend payment of estate tax under section 6166 that is made on or before August 30, 1980, may be revoked. To revoke an election, the executor must file a notice of revocation with the Internal Revenue Service office where the original estate tax return was filed on or before January 31, 1981 (or if earlier, the date on which the period of limitation on assessment expires). This notice of revocation must contain the decedent's name, date of death, and taxpayer identification number, and is to be accompanied by remittance of any additional amount of estate tax and interest determined to be due.

Examples. The provisions of this section may be illustrated by the following examples:

Based upon values shown on decedent A's timely filed estate tax return, 60 percent of the value of A's adjusted gross estate consisted of a farm which was a closely held business within the meaning of section 6166. A's executor, B, made a protective election under section 6166 when he filed A's estate tax return. B also applied for an extension of time under section 6161 to pay $15,000 of the $30,000 of estate tax shown due on the return. The requested extension was granted and was renewed at the end of 1 year. Eighteen months after the return was filed and after examination of A's estate tax return, the value of the farm was found to constitute 67 percent of the adjusted gross estate. B entered into an agreement consenting to the values as established on examination and to a deficiency of $5,000. B then filed a final notice of election under section 6166, choosing a 5-year deferral followed by 10 annual installment payments and thereby terminated his extension under section 6161 because that amount of tax was then included under the section 6166 election. B could have extended payment of 67 percent of the total estate tax, or $23,450. $23,450 is eligible for installment payments under section 6166 and the section section 6166 election is considered to be for that amount. B is considered to have prepaid $3,450 of tax since only $20,000 of tax remained unpaid. The $3,450 is attributed to the first installment of $2,345 and to $1,105 of the second installment which would have been payable under the section 6166 election.

Had B been granted an extension of time under section 6161 to pay $20,000 of tax, $25,000 would remain upaid when the final section 6166 election is made. Payment of the full $23,450 (67 percent) of tax which is attributable to the closely held business interest is included under the section 6166 election. The balance of unpaid tax ($1,550) is due upon expiration of the estate's section 6161 extension.

Assume the facts under example (1) (i). B must pay all unpaid accrued interest with his notice of final election. Since only 18 months have passed, no installments of tax are due. Interest on the $5,000 deficiency is computed at 4 percent per annum for the entire 18 months, and interest for 12 months of that period is currently due to be paid. Interest for the remaining 6 months is due at the next succeeding date for payment of interest. Interest on the $15,000 of tax extended under section 6161 is computed at the rate determined under section 6621 until the date of the final section 6166 election and is due upon termination of the section 6161 extension. After that date, the interest on the $15,000 will also accrue at 4 percent per annum.

Assume the facts as in example (1), except B initially made an election under section 6166A and made no protective election under section 6166. Following final determination of values, B is not permitted to make any election under section 6166; however, had B protectively elected section 6166 at the time he made the section 6166A election, he could have terminated the section 6166A election and finally elected under section 6166. In such a case, the full $23,450 of tax attributable to the farm would have been eligible for extension under section 6166. The 4 percent interest rate would apply to the $5,000 deficiency from the original due date of the tax, and, as with the extension under section 6161, it would apply to the amounts extended under section 6166A only from the date on which the election under section 6166 was finalized.

C died in 1977. His estate owes Federal estate taxes of $750,000, $500,000 of which is attributable to a closely held business interest. Payment of the $500,000 was extended under section 6166. A 5-year deferral followed by 10 annual installment payments was chosen by C's executor. Under paragraph (f) of this section, only 63.16 percent of each installment will be subject to the special 4 percent interest rate and the remainder will be subject to the rate determined under section 6621. The same rule applies in computing interest for the 5 years during which payment of tax is deferred. (This is so because the 4 percent interest rate applies only to a maximum of $345,800 of tax less the $30,000 of credit allowable under section 2010(a) rather than to the entire $500,000 extended amount).