A serial bond structure is one in which:

A serial bond structure is characterized by the portion of the issue's aggregate par value maturing at different intervals, typically annually. This means that rather than having a single maturity date for the entire bond issue, a series of maturities allows for smaller portions of the debt to be paid off over time. This structure can make debt management more manageable for issuers, as it can align with revenue streams and reduce the financial burden of large lump-sum payments.

This approach can also appeal to investors who may prefer receiving their principal back in installments rather than waiting until the end of the bond's life. The flexibility in repayment can be advantageous for both issuers and investors in terms of cash flow management.