23 CFR § 140.608
Reimbursable bond interest costs of Interstate projects
May 21, 2020
(a) Bond interest earned on bonds actually retired may be reimbursed on the Federal pro rata basis applicable to such projects in accordance with §140.602(b) and (c).
(b) No interest will be reimbursed for bonds issued after November 6, 1978, used to retire or otherwise refinance bonds issued prior to that date.