What Is an Annuity?
An annuity is a contract in which you pay an insurance company a lump sum or ongoing premiums, and in return the insurer pays you a stream of income, either starting immediately or at a future date. The defining feature of a lifetime annuity is longevity insurance: the payments continue as long as you live, no matter how long that turns out to be.
In finance more broadly, the word also describes any fixed series of equal cash flows, which is why annuity formulas show up constantly in time-value-of-money problems, bond math, and mortgage amortization. The present value of an annuity equals the payment times (1 - (1 + r)^-n) / r.
The Main Types
Immediate annuities start paying within a year of purchase, while deferred annuities accumulate value first and begin payouts later, often at retirement. Within each, a fixed annuity pays a guaranteed rate, a variable annuity ties payments to underlying investment performance, and an indexed annuity links returns to a market index with caps and floors.
As a concrete example, a 65-year-old paying $200,000 for a single-premium immediate annuity might receive roughly $1,100 to $1,300 per month for life, depending on prevailing interest rates. Higher rates at purchase mean higher lifetime payments, since the insurer can earn more on the premium.
Costs, Complexity, and Criticisms
Annuities are famous for opaque fees, and variable annuities in particular can layer administrative charges, mortality-and-expense fees, and rider costs that total 2% to 3% per year. Surrender charges can also lock up your money for five to ten years, penalizing early withdrawals.
Because many annuities pay generous sales commissions, they are sometimes pitched to people who do not need them. A young professional with decades of compounding ahead almost always builds wealth faster in low-cost index funds inside a 401(k) or IRA than inside a deferred annuity.
When an Annuity Actually Makes Sense
The strongest use case is a retiree who wants a guaranteed income floor covering essential expenses, effectively buying a private pension with part of their savings. Annuitizing a slice of a portfolio removes sequence-of-returns risk from that portion of spending.
For those earlier in their careers, the concept matters mostly as vocabulary and as valuation math. Understanding annuity pricing sharpens intuition for pensions, structured products, and any deal cash flows that arrive as level payments over time.
