CFR › Title 31 › Part 360 › §360.031 CFR §360.0Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗Copy link(a)The regulations in this part apply to definitive (paper) Series I savings bonds that have not been converted to book-entry bonds through TreasuryDirect®.(b)The regulations in 31 CFR part 363 apply to:(1)book-entry Series I savings bonds that were originally issued as book-entry bonds in TreasuryDirect®; and(2)definitive Series I savings bonds that have been converted to book-entry bonds through TreasuryDirect®.