Home › CFR › Title 26 › Part 48 › §48.4161(b)-526 CFR §48.4161(b)-5 — (b)-5 Effective date.Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗Copy linkThe taxes imposed by section 4161(b) are effective with respect to sales made on and after January 1, 1975.