An annuity is a contract between you and an insurance company that requires the insurer to make payments to you, either immediately or in the future. You buy an annuity by making either a single payment or a series of payments. Similarly, your payout may come either as one lump-sum payment or as a series of payments over time.

People typically buy annuities to help manage their income in retirement. Annuities provide three things:

• Periodic payments for a specific amount of time. This may be for the rest of your life, or the life of your spouse or another person.
• Death benefits. If you die before you start receiving payments, the person you name as your beneficiary receives a specific payment.
• Tax-deferred growth. You pay no taxes on the income and investment gains from your annuity until you withdraw the money.

Some people look to annuities to insure their retirement and to receive periodic payments once they no longer receive a salary. There are two phases to annuities, the accumulation phase and the payout phase.

• During the accumulation phase, you make payments that may be split among various investment options. In addition, variable annuities often allow you to put some of your money in an account that pays a fixed rate of interest.
• During the payout phase, you get your payments back, along with any investment income and gains. You may take the payout in one lump-sum payment, or you may choose to receive a regular stream of payments, generally monthly.

Variable annuities have a number of features that you need to understand before you invest. Understand that variable annuities are designed as an investment for long-term goals, such as retirement. They are not suitable for short-term goals because you typically will pay substantial taxes and charges or other penalties if you withdraw your money early. 

A life insurance policy is an example of a fixed annuity in which an individual pays a fixed amount each month for a pre-determined time period (typically 59.5 years) and receives a fixed income stream during their retirement years.

An example of an immediate annuity is when an individual pays a single premium, say $200,000, to an insurance company and receives monthly payments, say $5,000, for a fixed time period afterward. The payout amount for immediate annuities depends on market conditions and interest rates.

Annuities can be a beneficial part of a retirement plan, but annuities are complex financial vehicles. Because of their complexity, many employers don't offer them as part of an employee's retirement portfolio.

However, the passage of the Setting Every Community Up for Retirement Enhancement (SECURE) Act, signed into law by President Donald Trump in late December 2019, loosens the rules on how employers can select annuity providers and includes annuity options within 401(k) or 403(b) investment plans. The easement of these rules may trigger more annuity options open to qualified employees in the near future.