IUL Cap Rates Explained: How Caps Work and Change (2026)

What a cap rate is

An indexed universal life (IUL) policy lets you put cash value into index accounts. Each account credits interest based on how an index, most often the S&P 500, moved over a set period. The cap rate is the most that account can credit for the period, no matter how far the index rises.

Three settings work together on almost every index account:

• Cap: the ceiling on the credit.
• Participation rate: the share of the index gain that counts. At 100%, all of it counts, up to the cap.
• Floor: the minimum credit, usually 0%, so a falling index credits nothing rather than a loss.

The floor protects the index credit, not your cash value. The cost of insurance and other charges come out every month. In a year the index account credits 0%, those charges still reduce the cash value. Our IUL floor guide covers this in more detail.

You never own the index. The carrier credits interest by a formula tied to the index. Most accounts use the S&P 500 price index, so the dividends the companies pay are not part of the calculation. Allianz states this directly on its rate sheet: you cannot receive dividend payments from any index through the policy.

How a cap applies each crediting period

A cap is not an annual return target. It is applied once per crediting period, to that period's index change, and then it is done.

Here is the usual sequence on a one-year point-to-point account:

1. The segment starts. Money moves into the index account on a set date, with a cap the carrier has already declared.
2. The index is measured twice. Once on the start date and once a year later. Nothing in between counts on this method.
3. The credit is calculated. The percentage change, times the participation rate, limited by the cap and the floor.
4. The credit locks in. A later market drop cannot take it back. The next segment starts with a new cap, which may be higher or lower.

Two details catch people out. First, many policies track each premium as its own segment with its own start date and cap, so parts of your cash value can carry different caps. Second, money usually has to stay in the segment until the period ends. North American's consumer guide, for example, says index credits are only given if the segment still exists at the end of the period, and withdrawals or transfers before then reduce the credit.

Other methods, such as monthly sum or monthly average, apply caps differently. A monthly sum account caps each month's change, which is why its cap is much lower. Allianz Life Accumulator's monthly sum S&P 500 cap was 3.80% as of September 2026. See our index crediting methods guide for how each one works.

A worked example

Hypothetical. The index returns below are made up to show the math. They are not historical returns, a forecast, or the terms of any policy.

The first column of credits uses a 10% cap, 100% participation and a 0% floor. The other two show uncapped designs for comparison: one with a 60% participation rate, and one with a 6% spread, which subtracts 6 points from any gain.

What this shows:

• The cap costs you only in strong years. In the 15% and 25% years, the capped account gave up 5 and 15 points.
• The floor helps only in weak years. At -5%, the credit was 0% instead of a loss.
• Small and middle years favor the cap. At 3% and 8%, it kept the full gain; the uncapped designs caught up only in the 25% year.

The averages land close together here by coincidence; a different run of years would favor a different design. Every figure is a credit before charges. Your cash value grows by the credit minus the cost of insurance and other policy charges.

Want to test a cap against real index history? Our planned index crediting backtest runs any cap, participation rate, floor or spread over past S&P 500 years.

Caps vs participation rates vs spreads

All three limit the index credit. They just take their share at different points.

• A cap leaves small and middle gains alone and trims big ones.
• A participation rate below 100% takes a fixed share of every gain, big or small. A rate above 100% magnifies gains, usually on a custom index or with a charge.
• A spread subtracts a fixed number of points from any gain. Small gains can disappear completely.

Some accounts combine them, for example a participation rate above 100% with a cap. Nationwide's rate guide shows all three styles on one policy: IUL Accumulator II 2020, an older policy Nationwide has since replaced in its IUL lineup with IUL Accumulator III. As of March 2026, the S&P 500 one-year point-to-point account had a 10.25% cap with 100% participation, while the uncapped S&P 500 account used a 5.75% spread with 100% participation. See our participation rates guide for more.

Why carriers change caps

The carrier does not buy the index for you. It holds most of your cash value in its general account, mostly bonds, and uses a small slice of the expected yield to buy options on the index. The options pay off when the index rises. That slice is often called the option budget or hedge budget. The cap is roughly the highest level of index gain that budget can pay for.

Allianz describes this process in an SEC-filed prospectus for one of its index-linked annuities, and the same logic applies to IUL. It says index options are supported by bonds and other fixed income securities plus hedging instruments. It says the cost of the options changes with market conditions, and the company may adjust future caps and participation rates to reflect those changes. It lists the factors that move caps, including market volatility, hedging strategies and investment results, the availability of hedging instruments, the level of interest rates, and profit goals.

In plain terms, caps tend to fall when:

• Bond yields fall. Less yield means a smaller option budget. The NAIC notes that life insurers hold over 60% of their assets in bonds, and that lower rates reduce what those bonds earn.
• Options get more expensive. Options cost more when markets are volatile, so the same budget buys less upside.
• The carrier wants a bigger margin, or its hedging program costs more than planned.

Caps tend to rise when the reverse happens. The Federal Reserve's own record shows how much the rate backdrop moved: its target range sat at 0% to 0.25% from March 2020 to March 2022, reached 5.25% to 5.50% in July 2023, and was 3.75% to 4.00% after its September 2026 change. The Fed's policy rate is only one input, though. Insurers hold longer bonds bought over many years, so caps tend to move slowly. Allianz's prospectus warns that when rates rise, cap increases, if any, may be substantially slower than the rise in rates.

Guaranteed minimum caps

Every policy with a cap also has a guaranteed minimum cap in the contract. The carrier can cut the current cap on renewal, but never below this number. It is usually set when the policy is issued and does not change for the life of the policy.

Guaranteed minimums vary a lot, which is why they belong on your checklist:

These are current rates from each carrier's public rate sheet. They are not a ranking or a recommendation, and they will change. Availability varies by state.

A guaranteed minimum cap of 4%, and one that can be set as low as 0.25%, describe very different worst cases. Neither is a prediction. Both tell you how far the carrier is allowed to go.

What current S&P 500 caps look like

The table above doubles as a snapshot: as of our research, standard S&P 500 one-year point-to-point caps were 12.25% on Allianz Life Accumulator (as of September 2026) and 10.25% on Nationwide IUL Accumulator II 2020 (as of March 2026), an older policy Nationwide replaced in its IUL lineup with IUL Accumulator III, introduced in March 2026. Two data points are not a market survey, and we don't claim an industry average. Some carriers share current rates only with agents, so for other policies, current rates are available on request. Our planned IUL comparison tool will date every cap to the carrier document it came from.

How caps on in-force policies can be cut

The cap at sale applies to your first segments. After that, each new segment gets whatever cap the carrier declares for policies like yours at the time. That renewal cap can differ from the cap offered to new buyers of the same product.

Allianz's prospectus explains why: the main reason new-contract rates and renewal rates differ is the gap between what the company can earn on new investments and what it is earning on older investments it bought for existing contracts and holds to maturity. It also says plainly that the owner bears the risk that caps may be reduced.

What that means for you:

• A cap cut is legal and expected. As long as the new cap is at or above your guaranteed minimum, the carrier is within the contract.
• Your illustration assumes today's cap forever. If renewal caps fall, the policy will likely fall short of the illustration. With loans outstanding, that can raise lapse risk.
• Ask for the renewal history. Before you buy, ask how the carrier has set caps on policies it sold five and ten years ago compared with new ones. Our company reviews include a section on how each carrier treats existing policyholders.
• Watch your annual statement. It shows the caps applied to your segments. An in-force illustration run at current caps shows whether the policy is still on track.

Uncapped and participation strategies

Not every index account has a cap. The main alternatives:

• Uncapped with a participation rate below 100%. You keep a share of every gain with no ceiling.
• Uncapped with a spread. You keep the gain above a set number of points. Nationwide's uncapped S&P 500 account on IUL Accumulator II 2020 used a 5.75% spread as of March 2026, with a guaranteed maximum spread of 10%.
• High participation on a custom index. Many carriers offer participation rates well above 100% on volatility-controlled indexes. These indexes shift between stocks, bonds and cash to hold volatility down, which makes the options cheaper. Allianz Life Accumulator showed participation rates from 175% to 190% on its balanced custom indexes as of September 2026, with a 1% annual asset charge on its Select class. Many of these are excess return indexes. Allianz notes that, all else equal, higher short-term interest rates would make an excess return index underperform a non-excess-return version of the same index.

A high participation rate on a low-volatility index is not the same as a high participation rate on the S&P 500. Compare what the index itself has done, not just the multiplier on top.

Bonuses, multipliers and AG 49-A

Some policies boost index credits with a bonus, a multiplier, or a cap buy-up paid for by an extra charge. Examples from the rate sheets above:

• Nationwide's High Cap S&P 500 account on IUL Accumulator II 2020 raised the cap from 10.25% to 13.25% in exchange for a 1% indexed strategy charge, as of March 2026.
• Nationwide's Plus strategies on IUL Accumulator II 2020 added a 0.6% strategy credit, not guaranteed, with a guaranteed minimum of 0% (as of March 2026).

A charge-funded boost is not free money. In a year the index is flat or down, you pay the charge and receive nothing extra. The boost only pays off when the index does well enough to cover it.

Regulators noticed that these features made illustrations look better than plain policies. The NAIC's Actuarial Guideline 49-A, effective for policies sold on or after December 14, 2020, sets the rules:

• It defines a benchmark index account: S&P 500, one-year point-to-point, an annual cap, a 0% floor, 100% participation, no bonuses, and no charges used to raise the cap.
• The benchmark's maximum illustrated rate is the lower of two numbers: an average of past 25-year periods of S&P 500 history, calculated with the account's current cap, and 145% of the carrier's net investment earnings rate.
• Other accounts, including those with multipliers and bonuses, generally cannot illustrate better than the benchmark plus any extra option budget beyond the benchmark's, such as one paid for by an account charge.
• A 2023 revision, for policies sold on or after May 1, 2023, tightened the limits on those other accounts. The NAIC said its target was uncapped volatility-controlled accounts with a fixed bonus.
• The NAIC says a 2026 revision focused on consumer disclosures. The posted text applies to policies sold on or after April 1, 2026, and limits how historical returns can be shown in illustrations.

Our AG 49-A guide and bonuses and multipliers guide go further.

How to judge a cap

The highest illustrated cap is the easiest number to sell and one of the weaker reasons to buy. Weigh these instead:

1. The guaranteed minimum cap. It is the only cap you can count on.
2. Charges tied to the cap. A higher cap paid for by a strategy charge needs strong years to come out ahead.
3. The carrier's renewal record. Ask how caps on older policies compare with caps on new ones.
4. The whole account, not one term. Cap, participation rate, spread, floor and crediting method together decide the credit.
5. The policy's charges. A strong cap on an expensive policy can still leave you behind a modest cap on a cheaper one. See our IUL fees and charges guide.
6. The illustration at lower rates. Ask to see it run well below the maximum illustrated rate, and at guaranteed values, before you decide.
7. Financial strength. Every cap is only as good as the company behind it. Check the carrier's ratings in our company reviews.

If you already own a policy and your caps have dropped, our free policy review can show where it stands today.