An annuity cap is the maximum interest rate that can be credited to your account in a given crediting period, regardless of how much the index gained. If the S&P 500 returns 25% and your cap is 9%, you receive 9%. Caps typically range from 5% to 15%, depending on the contract and prevailing interest rate environment. Some contracts use a spread instead of a cap; they don’t use both simultaneously. Evaluate the cap in the context of the full crediting structure, not in isolation.