2025 Base Period T-Bill Rate.

Section 995(f)(1) of the Internal Revenue Code provides that a shareholder of a domestic international sales corporation (“DISC”) shall pay interest for each taxable year in an amount equal to the product of the “shareholder’s DISC-related deferred tax liability” for the year (as defined in section 995(f)(2)) and the “base period T-bill rate.” Under section 995(f)(4), the base period T-bill rate is “the annual rate of interest determined by the Secretary to be equivalent to the average of the 1-year constant maturity Treasury yields, as published by the Board of Governors of the Federal Reserve System, for the 1-year period ending on September 30 of the calendar year ending with (or of the most recent calendar year ending before) the close of the taxable year of the shareholder.”

The base period T-bill rate for the period ending September 30, 2025, is 4.08 percent.

Pursuant to section 6622 of the Internal Revenue Code, interest must be compounded daily. The table below provides factors for compounding the 2025 base period T-bill rate daily for any number of days in the shareholder’s taxable year (including for a 52-53 week taxable year). To compute the amount of the interest charge for the shareholder’s taxable year, multiply the amount of the shareholder’s DISC-related deferred tax liability for that year by the base period T-bill rate factor corresponding to the number of days in the shareholder’s taxable year for which the interest charge is being computed. Generally, one would use the factor for 365 days. One would use a different factor only if the shareholder’s taxable year for which the interest charge is being determined is a short taxable year, if the shareholder uses a 52-53 week taxable year, or if the shareholder’s taxable year is a leap year.

For the base period T-bill rates for periods ending in prior years, see Rev. Rul. 2024-27, 2024-51 I.R.B. 1240; Rev. Rul. 2023-23, 2023-51 I.R.B. 1472; Rev. Rul. 2022-21, 2022-47 I.R.B. 468; Rev. Rul. 2021-22, 2021-47 I.R.B. 726; Rev. Rul. 2020-25, 2020-48 I.R.B. 1109; and Rev. Rul. 2019-27, 2019-51 I.R.B. 1378.