3.2 How Life Insurance Works: Mortality, Interest, Reserves
Key Takeaways
- Premiums are built from three factors: mortality cost, expense loading, and assumed interest (investment earnings).
- Mortality tables such as the Commissioners Standard Ordinary (CSO) table give the probability of death at each age and drive the mortality charge.
- Higher assumed interest lowers premium; higher mortality or expenses raise it.
- Reserves are the insurer's liability set aside to pay future claims; the legal reserve insurer must hold reserves meeting state minimum standards.
- Net premium covers mortality and interest; gross premium adds the expense loading.
Pooling of Risk
Life insurance works by pooling the premiums of many insureds. In any year only a small, predictable fraction of a large group dies, so the pooled fund can pay large benefits to the few who die while remaining solvent. The larger and more homogeneous the pool, the more closely actual deaths track the predicted rate. This is the law of large numbers, and it is why insurers underwrite to keep each risk class similar.
Underwriting sorts applicants into rate classes such as preferred, standard, and substandard so that each pool is homogeneous. If an insurer mixed very high-risk and very low-risk lives at one price, healthier applicants would be overcharged and leave, a problem called adverse selection. Sound classification keeps the pooled mortality experience predictable and the price fair.
Mortality Tables
A mortality table (actuarial or life table) lists, for each age, the probability of dying within the next year and the number expected to survive. Actuaries use it to set the mortality charge.
The industry standard is the Commissioners Standard Ordinary (CSO) Mortality Table, adopted state by state for reserve and nonforfeiture calculations. Key points the exam tests:
- Tables are built from large population studies and are updated periodically as longevity improves.
- Death rates rise with age, so the mortality cost of pure protection rises every year.
- Tables historically separated male and female mortality; unisex tables are used where required.
Worked mortality cost
Suppose a table shows a death rate of 2 per 1,000 at a given age for a group of 100,000 insureds each holding $1,000 of pure protection.
| Item | Value |
|---|---|
| Insureds in pool | 100,000 |
| Death rate | 0.002 (2 per 1,000) |
| Expected deaths | 200 |
| Benefit per death | $1,000 |
| Total claims | $200,000 |
| Mortality cost per insured | $2.00 |
The $2.00 is the pure mortality cost before any expense or interest adjustment. Notice that if the same pool aged and the death rate climbed to 4 per 1,000, expected deaths would double to 400, total claims would reach $400,000, and the mortality cost per insured would rise to $4.00. This rising cost of pure insurance with age is the engine behind every premium pattern you will study.
The Three Pricing Factors
Every life premium is assembled from three building blocks. Remember the directional effect of each:
| Factor | What it is | Effect on premium |
|---|---|---|
| Mortality | Cost of expected death claims from the table | Higher mortality (older age, poorer health) raises premium |
| Interest | Investment earnings the insurer assumes on held premium | Higher assumed interest lowers premium |
| Expense (loading) | Commissions, underwriting, administration | Higher expenses raise premium |
The single most-missed exam point: interest works in the opposite direction from the other two. Because the insurer collects premium before it must pay claims, it invests that money; assumed earnings are credited in advance and reduce what the policyowner must pay.
Net Premium vs. Gross Premium
The pricing factors map onto two defined premiums.
- Net premium is calculated from mortality and interest only. It is the amount theoretically needed to fund future claims.
- Gross premium is the net premium plus the expense loading. It is the premium the policyowner actually pays.
So: Gross premium = Net premium + Loading, where the loading covers expenses and a margin. Payment mode also affects total cost: paying annually is cheapest in total, while monthly payments cost the most because of added administrative handling and lost interest to the insurer.
Reserves
A reserve is the amount an insurer holds today, plus assumed future premiums and interest, to guarantee it can pay future claims. Reserves are a liability on the insurer's books, not profit. State law sets minimum reserve standards (the insurer is a legal reserve company when it meets them), and the CSO table plus a maximum assumed interest rate drive the required reserve.
For level-premium permanent policies, early premiums exceed the current cost of insurance. The overcharge in early years is held in reserve and used to offset the rising mortality cost in later years. This is why a level premium can stay flat for life even though the underlying mortality cost climbs each year.
- Reserves protect policyowners by ensuring claim-paying ability.
- Reserves are tested for adequacy by the state insurance department.
- The reserve, net of expenses, is closely related to the policy's cash value in permanent products.
Two reserve methods appear on exams. The net level premium reserve assumes a constant premium across all years, producing a conservative, higher reserve. Modified reserve methods, such as the Commissioners Reserve Valuation Method (CRVM), allow a lower reserve in the first policy year to reflect heavy first-year acquisition expenses, then grade up to the full level reserve. Both must still satisfy the state's minimum standard. The practical takeaway is that reserves are forward-looking estimates of future liability, funded by the level premium overcharge in early years, and they are the foundation of an insurer's promise to pay.
An insurer raises the interest rate it assumes it will earn on invested premiums. All else equal, the effect on the premium charged to policyowners is that the premium will:
In a pool of 50,000 insureds each holding $1,000 of pure protection, the mortality table shows a death rate of 3 per 1,000. What is the pure mortality cost per insured for the year?
How the Three Factors Move Premiums
Life insurance premiums rest on three pricing factors, and the exam tests the direction each pushes premium:
| Factor | If It Increases | Effect on Premium |
|---|---|---|
| Mortality (expected deaths) | Higher death rate | Premium up |
| Interest (assumed earnings) | Higher assumed return | Premium down |
| Expenses (loading) | Higher costs | Premium up |
Mortality raises premium (more claims), interest lowers it (the insurer expects investment earnings to help fund benefits), and expenses (loading) raise it. The net premium considers only mortality and interest; adding the expense loading produces the gross premium the policyowner actually pays.
Holding everything else constant, if an insurer assumes a HIGHER interest (investment) earnings rate, the life insurance premium will tend to:
Reserves and the Net Amount at Risk
Reserves are liabilities the insurer holds to guarantee future claims a regulated savings buildup matched to expected obligations. As reserves and cash value grow in a permanent policy, the net amount at risk (death benefit minus reserve/cash value) shrinks, which is why level-premium policies remain affordable as the insured ages.
Mortality tables (like the Commissioners Standard Ordinary table) provide the expected death rates by age. Because actual mortality among many insureds closely follows the table (the law of large numbers), the insurer can price confidently across the pool.
Exam Tip: Net premium = mortality + interest; gross premium adds expense loading. Reserves are the insurer's liability ensuring future claims can be paid.