The issuer of a municipal bond receives a cash purchase price at the time of issuance in exchange for a promise to repay the purchasing investors, or their transferees, (the bond holder) over time. Repayment periods can be as short as a few months (although this is very rare) to 20, 30, or 40 years, or even longer. The issuer typically uses proceeds from a bond sale to pay for capital projects or for other purposes it cannot or does not desire to pay for immediately with funds on hand. Tax regulations governing municipal bonds generally require all money raised by a bond sale to be spent on capital projects within three to five years of issuance. Certain exceptions permit the issuance of bonds to fund other items, including ongoing operations and maintenance expenses in certain cases, the purchase of single-family and multi-family mortgages, and the funding of student loans, among many other things.