A tax is hereby imposed on the transfer of the taxable estate of every decedent who is a citizen or resident of the United States.

The tax imposed by this section shall be the amount equal to the excess (if any) of—

a tentative tax computed under subsection (c) on the sum of—

(A) the amount of the taxable estate, and

(B) the amount of the adjusted taxable gifts, over

(2) the aggregate amount of tax which would have been payable under chapter 12 with respect to gifts made by the decedent after December 31, 1976, if the modifications described in subsection (g) had been applicable at the time of such gifts.

If the amount with  respect to which the  tentative tax to be  computed is: The tentative is: Not over $10,000 18 percent of such amount. Over $10,000 but not over $20,000 $1,800, plus 20 percent of the excess of such amount over $10,000. Over $20,000 but not over $40,000 $3,800, plus 22 percent of the excess of such amount over $20,000. Over $40,000 but not over $60,000 $8,200 plus 24 percent of the excess of such amount over $40,000. Over $60,000 but not over $80,000 $13,000, plus 26 percent of the excess of such amount over $60,000. Over $80,000 but not over $100,000 $18,200, plus 28 percent of the excess of such amount over $80,000. Over $100,000 but not over $150,000 $23,800, plus 30 percent of the excess of such amount over $100,000. Over $150,000 but not over $250,000 $38,800, plus 32 percent of the excess of such amount over $150,000. Over $250,000 but not over $500,000 $70,800, plus 34 percent of the excess of such amount over $250,000. Over $500,000 but not over $750,000 $155,800, plus 37 percent of the excess of such amount over $500,000. Over $750,000 but not over $1,000,000 $248,300, plus 39 percent of the excess of such amount over $750,000. Over $1,000,000 $345,800, plus 40 percent of the excess of such amount over $1,000,000.

For purposes of subsection (b)(2), if—

(1) the decedent was the donor of any gift one-half of which was considered under section 2513 as made by the decedent’s spouse, and

(2) the amount of such gift is includible in the gross estate of the decedent,

If—

(1) the decedent’s spouse was the donor of any gift one-half of which was considered under section 2513 as made by the decedent, and

(2) the amount of such gift is includible in the gross estate of the decedent’s spouse by reason of section 2035,

If the time has expired under section 6501 within which a tax may be assessed under chapter 12 (or under corresponding provisions of prior laws) on—

If the time has expired under section 6501 within which a tax may be assessed under chapter 12 (or under corresponding provisions of prior laws) on—

(A) the transfer of property by gift made during a preceding calendar period (as defined in section 2502(b)); or

(B) an increase in taxable gifts required under section 2701(d),

For purposes of paragraph (1), a value shall be treated as finally determined for purposes of chapter 12 if—

(A) the value is shown on a return under such chapter and such value is not contested by the Secretary before the expiration of the time referred to in paragraph (1) with respect to such return;

(B) in a case not described in subparagraph (A), the value is specified by the Secretary and such value is not timely contested by the taxpayer; or

(C) the value is determined by a court or pursuant to a settlement agreement with the Secretary.

For purposes of applying subsection (b)(2) with respect to 1 or more gifts, the rates of tax under subsection (c) in effect at the decedent’s death shall, in lieu of the rates of tax in effect at the time of such gifts, be used both to compute—

For purposes of applying subsection (b)(2) with respect to 1 or more gifts, the rates of tax under subsection (c) in effect at the decedent’s death shall, in lieu of the rates of tax in effect at the time of such gifts, be used both to compute—

(A) the tax imposed by chapter 12 with respect to such gifts, and

(B) the credit allowed against such tax under section 2505, including in computing— (i) the applicable credit amount under section 2505(a)(1), and (ii) the sum of the amounts allowed as a credit for all preceding periods under section 2505(a)(2).

The Secretary shall prescribe such regulations as may be necessary or appropriate to carry out this section with respect to any difference between—

(A) the basic exclusion amount under section 2010(c)(3) applicable at the time of the decedent’s death, and

(B) the basic exclusion amount under such section applicable with respect to any gifts made by the decedent.

(Aug. 16, 1954, ch. 736, 68A Stat. 373; Pub. L. 94–455, title XX, § 2001(a)(1), Oct. 4, 1976, 90 Stat. 1846; Pub. L. 95–600, title VII, § 702(h)(1), Nov. 6, 1978, 92 Stat. 2930; Pub. L. 97–34, title IV, § 402(a)–(c), Aug. 13, 1981, 95 Stat. 300; Pub. L. 98–369, div. A, title I, § 21(a), July 18, 1984, 98 Stat. 506; Pub. L. 100–203, title X, § 10401(a)–(b)(2)(A), Dec. 22, 1987, 101 Stat. 1330–430, 1330–431; Pub. L. 103–66, title XIII, § 13208(a)–(b)(2), Aug. 10, 1993, 107 Stat. 469; Pub. L. 105–34, title V, §§ 501(a)(1)(D), 506(a), Aug. 5, 1997, 111 Stat. 845, 855; Pub. L. 105–206, title VI, § 6007(e)(2)(B), July 22, 1998, 112 Stat. 810; Pub. L. 105–277, div. J, title IV, § 4003(c), Oct. 21, 1998, 112 Stat. 2681–909; Pub. L. 107–16, title V, § 511(a)–(c), June 7, 2001, 115 Stat. 70; Pub. L. 111–312, title III, § 302(a)(2), (d)(1), Dec. 17, 2010, 124 Stat. 3301, 3302; Pub. L. 112–240, title I, § 101(c)(1), Jan. 2, 2013, 126 Stat. 2317; Pub. L. 115–97, title I, § 11061(b), Dec. 22, 2017, 131 Stat. 2091.)