A single premium immediate annuity offers an income stream that will last as long as the annuitant (or joint annuitant, if that option is selected) lives or for a predetermined period, depending on the option selected at the time of purchase. The fixed immediate annuities include nominal, graded and inflation-adjusted payment options. There is also a variable option in which the payout is determined by the returns on the investments chosen by the investor.
In exchange for these payments, the annuitant surrenders a specific amount of money to the insurance company. These payments can be based on a single or joint life. Normally this purchase is irrevocable, and the money used to make the SPIA purchase is not available to one's heirs, even if the annuitant dies shortly after purchasing the annuity, unless a predetermined payment period was selected. However, selecting one of the available term-certain payment options will result in lower payments.
An SPIA is probably one of the easiest annuity products to understand. You give the insurance company a specific sum of money in exchange for an income stream that you can't outlive. The SPIA can offer peace of mind in bridging income shortages. For example, if a retired couple needs $4,000 per month to cover their living expenses, and Social Security and pensions provide $3,000 per month, they could purchase an SPIA that would pay out the needed $1,000 per month for as long as either one of them lived. However, they would need to keep in mind that most annuity payments aren't indexed for inflation, so over the long term, the spending power of that $1,000 would decrease.
Should the couple choose to purchase one of the few inflation-indexed SPIAs available, they'd have to either pay a higher premium or receive a lower initial payment. And since inflation-indexed annuities are only offered by a few insurance companies, there's not a lot of competition to help make those rates attractive for the annuitant. Finally, it's important to remember that the return of your principal is included in the promised payment stream.
An SPIA can also provide a "bridge" that could allow an investor to delay taking Social Security until later in life. Doing so could mean larger Social Security payments to both the recipient and his/her spouse. Boglehead Ron explained his use of an SPIA this way: "In our case, we used it as ‘SS gap insurance' since I retired at 59 but will not claim SS till age 70 (primarily for the benefit of my wife)."
