26 CFR § 31.3406(a)-4 - Time when payments are considered to be paid and subject to backup withholding.
(a) Timing—(1) In general. If backup withholding is required under section 3406 on a reportable payment (as defined in section 3406(b)), the payor must withhold at the time it makes the payment to the payee or to the payee's account that is subject to withholding. Amounts are considered paid when they are credited to the account of, or made available to, the payee. Amounts are not considered paid solely because they are posted (e.g., an informational notation on the payee's passbook) if they are not actually credited to the payee's account or made available to the payee. See paragraph (c) of this section for the timing of withholding by a middleman.
(2) Special rules for dividends. For purposes of section 3406 and this section—
(i) Record date earlier than payment date. In the case of stock for which the record date is earlier than the payment date, the dividends are considered paid on the payment date.
(ii) Dividends paid in corporate reorganizations. In the case of a corporate reorganization, if a payee is required to exchange stock held in the former corporation for stock in the new corporation before the dividends that have been paid with respect to the stock in the new corporation will be provided to the payee, the dividend is considered paid on the date the payee actually exchanges the stock and receives the dividend.
(b) Amounts reportable under section 6045—(1) In general. Notwithstanding paragraph (a) of this section, in the case of a transaction reportable under section 6045 (except in the case of forward contracts (including foreign currency contracts), regulated futures contracts, and security short sales), the obligation to withhold under section 3406 arises on the date the sale is entered on the books of the broker or the date the exchange occurs as provided in § 1.6045–1(f)(3) of this chapter. A broker (in its capacity as payor) is not required, however, to satisfy its withholding liability until payment is made. See § 31.3406(b)(3)–2(b)(2) for special rules applicable to forward contracts (including foreign currency contracts), regulated futures contracts, and security short sales.
(2) Special rule for interest accrued on bonds. For purposes of determining the time that interest is considered paid and subject to withholding under section 3406 when bonds are sold between interest payment dates, the portion of the sales price representing interest accrued to the date of sale is considered a portion of a reportable payment of gross proceeds under section 6045 (provided that the accrued interest is not tax-exempt as described in section 103(a), relating to certain governmental obligations), and is not considered to be a payment of interest for purposes of section 6049.
(c) Middlemen—(1) In general. A person that is a middleman and is a person defined in § 31.3406(a)–2(b) or in the section on information reporting to which the payment relates must withhold under section 3406 at the time the reportable payment is received by or credited to the middleman. If the middleman makes or credits the reportable payment to the payee prior to the middleman's receipt of the corresponding payment, the middleman may withhold at the time the reportable payment is made or credited to the payee.
(2) Special rule for common trust funds. A common trust fund (as defined in section 584) must withhold either—
(i) At the time the reportable payment is received by or credited to the common trust fund as provided in paragraph (c)(1) of this section;
(ii) On the date on which the assets of the common trust fund are valued; or
(iii) At the time the common trust fund pays or credits the reportable payment to a participant of the common trust fund.
(3) Special rule for certain grantor trusts. For grantor trusts described in § 31.3406(a)–2(b)(1) or (2), reportable payments made to the trust are treated as paid by the trust to each grantor, in an amount equal to the distribution made by the trust to each grantor, on the date that the reportable payment is paid to the trust (except for gross proceeds reportable under section 6045). Paragraph (b)(2) of this section applies to a grantor trust making a payment of gross proceeds under section 6045 subject to withholding under section 3406. For purposes of this paragraph (c)(3) a husband and wife filing a joint return are considered to be one grantor.