An immediate annuity is an insurance product that provides guaranteed income: You give an insurer a chunk of money, and the company gives you a stream of payments that can last for life.... If you don’t have enough guaranteed income to cover essential living costs, though, an immediate annuity could fill in the gap, says Wade Pfau, author of “ Retirement Planning Guidebook.” But immediate annuities shouldn’t be an “ all or nothing ” solution, Pfau says.... The steady stream of income could hel