Series I savings bonds that were originally issued as definitive bonds may be converted to book-entry bonds through TreasuryDirect®, an online system for holding Treasury securities. The Web address for TreasuryDirect® is www.treasurydirect.gov. Bond owners who wish to convert their definitive savings bonds should follow online instructions for conversion. Regulations governing converted bonds are found at 31 CFR part 363.
31 C.F.R. §360.3