Does interest start to accrue on purchase date or settlement date for bonds?

For the purposes of calculating interest income after one has purchased a bond, interest begins to accrue on the settlement date of the purchase (not the trade date.) Unlike stocks, the ownership of which begins on trade date, ownership of a bond begins on settlement date. Therefore, settlement date can be thought of as the purchase date. In order to calculate "accrued interest", or interest payable to the seller, at the time of purchase, the accrual period begins on the date of the last interest payment or the original issue date if the first interest payment has not yet occurred. Accriued interest is calculated through the day immediately preceding the settlement date.