A bond offer allows terminating the relationship between the issuer and investor before the maturity date. There are two types. With a non-callable offer, the investor has the right to present the security for repurchase: they decide whether to continue holding the issue or receive the par value early. With a callable offer, the issuer has the right to early redemption.
The practical significance of a non-callable offer is often related to coupon changes: the issuer sets the rate only until the offer date, then announces a new one. If it proves unacceptable, the investor presents the security for repurchase. Those who miss the submission deadline remain with the new coupon, which may be significantly lower than the previous one.
A callable offer works against the investor: the issuer exercises the early redemption right when rates fall and refinancing becomes cheaper. The investor receives their money back at that moment and must reinvest it at lower returns.
Hence the rule: the presence of an offer changes the actual investment period, and returns should be calculated not to maturity but to the nearest offer. The submission date and procedure for filing a claim should be clarified in advance—the procedure requires active actions from the bondholder.