# § 644. Taxable year of trusts
**(a)** **In general** For purposes of this subtitle, the taxable year of any trust shall be the calendar year.
**(b)** **Exception for trusts exempt from tax and charitable trusts** Subsection (a) shall not apply to a trust exempt from taxation under section 501(a) or to a trust described in section 4947(a)(1).
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**Source Credit**: (Added Pub. L. 99–514, title XIV, § 1403(a), Oct. 22, 1986, 100 Stat. 2713, § 645; renumbered § 644, Pub. L. 105–34, title V, § 507(b)(1), Aug. 5, 1997, 111 Stat. 856.)
## Editorial Notes
### Prior Provisions
A prior section 644, added , , ; amended –(3), , ; , , ; , , , related to special rule for gain on property transferred to trust at less than fair market value, prior to repeal by , , .
### Amendments
1997— renumbered as this section.
## Statutory Notes and Related Subsidiaries
### Effective Date of 1997 Amendment
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### Effective Date; Transition Rule
> **“(1)** **Effective date.—** The amendments made by this section [enacting this section] shall apply to taxable years beginning after December 31, 1986.
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> **“(2)** **Transition rule.—** With respect to any trust beneficiary who is required to include in gross income amounts under sections 652(a) or 662(a) of the Internal Revenue Code of 1986 in the 1st taxable year of the beneficiary beginning after December 31, 1986, by reason of any short taxable year of the trust required by the amendments made by this section, such income shall be ratably included in the income of the trust beneficiary over the 4-taxable year period beginning with such taxable year.”
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### Application of Transition Rules to Trust Beneficiaries to Which Section 664 Applies
> **“(1)** If a beneficiary of a trust to which section 664 of the 1986 Code applies elects (at such time and in such manner as the Secretary of the Treasury or his delegate may prescribe) to have this paragraph apply, such beneficiary shall be entitled to the benefits of section 1403(c)(2) of the Reform Act [Pub. L. 99–514, set out as an Effective Date; Transition Rule note above] with respect to amounts included in gross income under section 664(b) of the 1986 Code in the same manner as if such amounts were included in gross income under section 652(a) of the 1986 Code.
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> **“(2)** Any trust beneficiary may elect (at such time and in such manner as the Secretary of the Treasury or his delegate may prescribe) to waive the benefits of section 1403(c)(2) of the Reform Act.
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> **“(3)**
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> **(A)** For purposes of determining the gross income of any pass-thru entity, such pass-thru entity shall not be allowed the benefits of section 806(e)(2)(C) [Pub. L. 99–514, set out as an Effective Date of 1986 Amendment note under section 1378 of this title] (other than with respect to income from a common trust fund) or 1403(c)(2) of the Reform Act if such pass-thru entity is required to change its taxable year by reason of the amendments made by section 806 or 1403 of the Reform Act [Pub. L. 99–514, which enacted this section and amended sections 267, 441, 706, and 1378 of this title].
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> **“(B)** For purposes of subparagraph (A), the term ‘pass-thru entity’ means any trust, partnership, S corporation, or common trust fund.
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> **“(4)** If any trust was required to change its taxable year by the amendments made by section 1403 of the Reform Act [Pub. L. 99–514, which enacted this section], such change shall be treated as initiated by such trust and approved by the Secretary of the Treasury or his delegate.”
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