An annuity buys an income by giving up the capital

This works through annuities in the order the parts actually depend on each other.

What is actually being purchased

An annuity converts a lump sum into an income payable for life, or for a defined period, depending on the type. The purchaser gives up the capital permanently and receives in exchange a payment that cannot be outlived. What is being bought is therefore insurance against living a long time, which is a risk no individual can diversify alone.

The insurer can pool that risk across many people, which is why the product exists at all. Describing an annuity as an investment misses the point; it is a transfer of longevity risk with an income attached.

How the pricing works

The income offered depends on prevailing interest rates, on life expectancy at the purchaser's age, and on any features attached. Higher interest rates generally allow higher incomes for the same capital, which is why annuity rates move with bond markets.

In numbers, age matters because a shorter expected payment period allows a higher annual payment from the same sum. Health and lifestyle can also affect pricing, and in some markets impaired life annuities pay more to those with reduced life expectancy. Disclosing health conditions accurately is therefore in the purchaser's interest, which is unusual among financial products.

The options that reduce the income

A joint annuity continues paying a survivor, which costs income now in exchange for protection later. An escalating annuity increases payments over time, starting lower and rising, which addresses the erosion of purchasing power. A guarantee period pays for a minimum number of years even if the purchaser dies early, protecting against a very early death.

Each of these is priced, so each reduces the starting income, and the reductions are cumulative. Choosing options is therefore a series of trade-offs between income now and protection against specific scenarios.

The permanence

Once purchased, an annuity generally cannot be reversed, sold or altered, which distinguishes it from almost every other financial arrangement. That permanence is what allows the insurer to price it, since the pooling depends on the commitment being fixed.

Practically, it also means the decision should be made once and carefully, with full information about the alternatives. Some purchasers annuitise part of a pot and leave the remainder flexible, which addresses both certainty and adaptability.

Whether that is appropriate depends entirely on circumstances, which is why regulated advice matters here.

What it protects against

The specific protection is against outliving your money, which is the risk that grows more serious the longer retirement lasts. It also removes exposure to markets for that portion of the money, which some retirees value highly. Against that, it removes the possibility of leaving that capital to anyone, which matters where dependants exist.

It also fixes the income, so an annuity without escalation loses purchasing power steadily across a long retirement. Weighing those characteristics is a personal question rather than a technical one.

The right answer depends on your tax situation, which this cannot see.

Availability and jurisdiction

Annuity markets differ enormously between countries, and in some places the product is compulsory, common or effectively unavailable. Tax treatment of the income also differs, and it can depend on where the money came from.

The arithmetic is straightforward: where a market exists, shopping around rather than accepting a provider's default offer has historically produced materially different outcomes. The regulatory protections attached to such purchases vary, and it is worth confirming what applies locally. This is general information about how annuities work and is not a recommendation to buy or avoid one.

The takeaway

You are buying insurance against living a long time. Every option you add to it is paid for out of the income.

The decision is rarely about picking the best option — it is about avoiding the expensive one.