3.2 How Life Insurance Works: Mortality, Interest, Reserves
Key Takeaways
- Life insurance pools risk; the three pricing factors are mortality and expenses (which raise premiums) and interest (which lowers them).
- Gross premium equals net premium plus loading; the net premium reflects only mortality and interest.
- The 2017 Commissioners Standard Ordinary (CSO) mortality table is the current U.S. standard and sets minimum reserve requirements.
- Level premiums create reserves: early overpayments accumulate with interest to fund higher mortality costs in later years.
- Net amount at risk equals death benefit minus cash value, and it decreases as cash value grows.
Life insurance works through the pooling of risk: many insureds pay premiums into a common fund, and the relatively few who die in a given year are paid from it. Because actuaries can predict group mortality with great accuracy even though they cannot predict any individual's death, the pool stays solvent while delivering large benefits.
Three variables determine the premium an insurer charges. On the national exam these are tested constantly: mortality, interest, and expenses. A useful memory device is that mortality and expenses raise the net premium while interest lowers it.
The Three Pricing Factors
| Factor | Effect on premium | Why |
|---|---|---|
| Mortality | Higher mortality → higher premium | More expected death claims to fund |
| Interest | Higher assumed interest → lower premium | Insurer earns investment income, so it needs less premium today |
| Expenses (loading) | Higher expenses → higher premium | Covers commissions, administration, taxes |
The net premium uses mortality and interest only. Adding the loading for expenses produces the gross premium the policyholder actually pays. Remember: Gross premium = net premium + loading.
Mortality Tables
A mortality table (life table) shows the probability of death at each age per 1,000 lives. Actuaries read mortality risk from these tables. The U.S. standard is the Commissioners Standard Ordinary (CSO) table; the 2017 CSO table is the current version and reflects longer life expectancy than earlier tables.
- Death rates rise with age, so the cost of pure insurance increases every year an insured grows older.
- Mortality tables set minimum reserve standards that insurers must hold.
- Separate experience is used for different risk classes (e.g., smoker vs. nonsmoker).
Why Level Premiums Create Reserves
If an insurer charged the true annual cost of insurance each year, premiums would start cheap and climb steeply as mortality rises — eventually becoming unaffordable. Instead, permanent policies use a level premium: the insured overpays in early years (when actual mortality cost is low) and underpays in later years (when mortality cost is high).
The early overpayments accumulate, with interest, into the reserve — a liability on the insurer's books representing the funds set aside to pay future claims. The reserve is the engine behind a permanent policy's cash value.
Reserves and Solvency
The reserve is a liability, not the insurer's profit. State law and the CSO table dictate the minimum legal reserve an insurer must maintain so it can meet future obligations.
- Legal (statutory) reserve — the regulator-required minimum, designed to keep the insurer solvent.
- Policy reserve — the per-policy liability that, with future net premiums and interest, will equal future benefits.
Exam framing: Reserves protect policyholders' future claims; they are a measure of the insurer's obligations, not its surplus. Strong reserves are why a level-premium permanent policy can guarantee a death benefit for life.
Net Amount at Risk
In a cash-value policy, the death benefit is funded partly by the policy's own cash value and partly by the insurer's pure insurance. The insurer's exposure is the net amount at risk:
Net amount at risk = Death benefit − Cash (reserve) value
Example: A whole life policy has a $100,000 face amount and $22,000 of cash value. The net amount at risk the insurer must cover from the mortality pool is $100,000 − $22,000 = $78,000. As cash value grows over the years, the net amount at risk shrinks, which is precisely how a level premium remains adequate even though per-unit mortality cost keeps rising.
All other factors held constant, if an insurer raises the interest rate it assumes it will earn on invested premiums, what is the effect on the premium charged?
A whole life policy has a $250,000 death benefit and accumulated cash value of $60,000. What is the insurer's net amount at risk?
Premium Modes, Loading, and the Role of Interest
Three components build every premium: mortality (the cost of expected death claims), interest (the assumed earnings on reserves, which reduces premium), and expenses/loading (commissions, administration, and contingency). Together they form the gross premium; mortality minus interest gives the net premium before loading.
The payment mode also affects total cost. Paying more frequently than annually adds an interest and billing charge, so the more frequent the mode, the higher the aggregate yearly outlay.
| Mode | Relative annual cost |
|---|---|
| Annual | Lowest total |
| Semi-annual | Slightly higher |
| Quarterly | Higher |
| Monthly | Highest total |
Worked idea: If an insurer assumes a higher interest rate on its reserves, it expects investments to cover more of the future claim, so it can charge a lower premium today. Conversely, rising mortality assumptions or expense loads push premiums up.
Trap: Interest is the only one of the three factors that lowers the premium; mortality and expense both raise it. Examiners test whether you can predict the direction a change in each assumption moves the premium.