Why premiums alone cannot be compared
A $600 term premium and a $6,000 whole life premium are not ten times apart in cost, and they are not comparable at all as written. The whole life premium buys three things at once: the same death benefit the term policy provides, a savings account inside the contract, and a guarantee that the coverage never expires and the premium never rises. Comparing the headline numbers prices all three as if they were one.
Regulators solved this in the 1970s with the interest-adjusted cost indexes, which the NAIC's Life Insurance Disclosure Model Regulation requires insurers to disclose. They do three things the old method did not: they accumulate premiums at interest, so a dollar paid in year one counts for more than a dollar paid in year twenty; they credit dividends the same way; and they express the answer per $1,000 of death benefit per year, so policies of different sizes can be laid side by side.
Two indexes exist because there are two ways a policy ends.
- The surrender cost index subtracts the cash surrender value, so it answers: what did the coverage cost me per year per $1,000 if I cash the policy in at the end of the period?
- The net payment cost index does not subtract it, so it answers: what did it cost if I keep the policy until I die and the cash value is never realised?
The gap between them is the cash value, annuitised. On a term policy the two are identical, because there is no cash value to subtract — which is itself a clean way of seeing what a permanent policy adds.
The index, term by term, and what the traditional method got wrong
Accumulate the premiums. Take each annual premium forward to the end of the period at the index rate, treating them as an annuity due because premiums are paid at the start of each year. At 5% over 20 years the accumulation factor for $1 a year is 34.719252, so $6,000 a year accumulates to $208,315.51.
Subtract the accumulated dividends. Same treatment, opposite sign. A participating policy's dividends reduce the net cost, and treating them as though they were received today would overstate their effect.
Subtract the cash surrender value — for the surrender index only. It is already a year-n figure, so no accumulation applies.
Divide twice. First by the annuity factor, which converts a lump sum at year n into the level annual amount that would produce it. Then by the face amount in thousands, which puts the answer on a per-$1,000 basis. What comes out is a number you can compare across carriers, across face amounts, and across product types.
Why the traditional net cost method was abandoned. The old method was simply premiums minus dividends minus cash value, with no interest. It produced negative net costs routinely — the default figures on this page give −$10,000, which reads as though twenty years of half-million-dollar coverage were free and the insurer paid you $10,000 for the privilege. It is not free. The method ignores that you gave up the use of $6,000 a year for twenty years. The interest-adjusted index restores that, and the same policy comes out at $4.51 per $1,000 per year on a surrender basis. The traditional figure is shown on this page only so you can see the size of the distortion.
The break-even return is the comparison that actually decides things. Instead of asserting a market return and declaring a winner, solve for the return at which the two strategies tie. Invest the premium difference each year, and find the rate at which the side fund at year n exactly equals the policy's cash surrender value. If that rate is below what you believe you can earn, the invested difference wins; if it is above, the policy does. It converts an argument about products into a single, checkable number.
Worked example: $500,000 of coverage over twenty years
A $500,000 whole life policy costs $6,000 a year. A 20-year level term policy for the same face amount costs $600 a year. The illustration shows a cash surrender value of $130,000 at the end of year 20. The policy is non-participating, so dividends are zero. You assume 7% on a side fund and use the standard 5% index rate.
- Accumulate the premiums. $6,000 as an annuity due for 20 years at 5%: 6,000 × [(1.0520 − 1) ÷ 0.05] × 1.05 = 6,000 × 33.065954 × 1.05 = $208,315.51.
- Annuity due factor for $1. 33.065954 × 1.05 = 34.719252.
- Net payment cost index. 208,315.51 ÷ 34.719252 ÷ 500 = $12.00 per $1,000 per year. With no dividends this is just the premium per $1,000, and it has to be: 6,000 ÷ 500 = 12.00.
- Surrender cost index. (208,315.51 − 130,000) ÷ 34.719252 ÷ 500 = 78,315.51 ÷ 34.719252 ÷ 500 = $4.51 per $1,000 per year.
- Traditional net cost. $6,000 × 20 − $130,000 = −$10,000. Negative, and meaningless.
Now the side fund. You pay $600 for term and invest the other $5,400 each year.
- Side fund at 7%. 5,400 × [(1.0720 − 1) ÷ 0.07] × 1.07 = 5,400 × 40.995492 × 1.07 = $236,871.95.
- Against the cash value. $236,871.95 − $130,000 = $106,872 ahead, before tax on the side fund's gain.
- Break-even return. The rate at which 5,400 a year for 20 years accumulates to exactly $130,000 is 1.73%.
That last figure is the whole argument in one number. The policy's cash value is equivalent to earning 1.73% a year on the money you would otherwise have invested. Whether you should buy it depends on whether you can reliably beat 1.73% after tax over twenty years, and on how much you value the three things the term policy does not give you: coverage that never expires, a premium that never rises, and a guaranteed floor under the cash value. At 1.73% the market answer is easy; the insurance answer is not, and it is the one the needs analysis should settle first.
How to read the result
Compare cost indexes only between policies with the same face amount, the same insured, the same period and the same index rate. That is what makes them comparable at all. A surrender cost index of $4.51 against another carrier's $5.80 on identical terms is a genuine $1.29 per $1,000 per year difference — on $500,000 of coverage, $645 a year. Against a policy quoted at 10 years rather than 20, it means nothing.
Choose the index that matches your intention. If you might surrender, use the surrender cost index. If the policy is being bought to be held until death — estate liquidity, a lifelong dependant, a buy-sell obligation — use the net payment cost index, because you will never see the cash value. Salespeople quote the surrender index because it is always the lower of the two.
The break-even return is the honest headline. Read it as the guaranteed, tax-deferred rate the policy's savings component delivers over the period you tested. Compare it to what you would actually hold in a taxable account, at the risk you would actually take — not to a long-run equity average you would need thirty years and a strong stomach to realise.
Two things the side fund never provides. First, coverage after the term expires: the calculator warns when the comparison period runs past the term length, and beyond that point the term strategy has no death benefit at all. Second, the guarantee. A whole life cash value has a contractual floor; a side fund does not. Whether that floor is worth the difference is a preference, but it should be priced, and the break-even return is the price.
Tax is not in the side fund figure. Gains in a taxable account are taxed on realisation, and gains on a surrendered policy are taxed as ordinary income above basis. The cash value return calculator handles both explicitly and is the right tool once the pre-tax comparison is close.
Surrender cost index per $1,000, on $500,000 of coverage over 20 years
| Annual premium | FV of premiums | CSV $60,000 | CSV $90,000 | CSV $120,000 | CSV $150,000 |
|---|---|---|---|---|---|
| $4,000 | $138,877 | $4.54 | $2.82 | $1.09 | −$0.64 |
| $5,000 | $173,596 | $6.54 | $4.82 | $3.09 | $1.36 |
| $6,000 | $208,316 | $8.54 | $6.82 | $5.09 | $3.36 |
| $7,000 | $243,035 | $10.54 | $8.82 | $7.09 | $5.36 |
| $8,000 | $277,754 | $12.54 | $10.82 | $9.09 | $7.36 |
The one negative cell is not an error and not free insurance — it means that at a 5% index rate the cash value exceeds the accumulated premiums, which a policy can do at the far end of a long period. It is rare, and it is exactly the regime in which you should check the illustration's guarantees rather than its projections.
Comparison errors that change the answer
- Comparing indexes across different periods. A 10-year index and a 20-year index on the same policy differ substantially, because acquisition costs are spread over twice as many years. Match the periods.
- Using illustrated cash values as if they were guaranteed. Most illustrations show a current column and a guaranteed column. Run the index on both — if the ranking flips, the decision is being made by a projection the insurer can change.
- Assuming you would actually invest the difference. The whole term strategy depends on it. If the money would be spent, the comparison is theoretical and the policy's forced-saving discipline has real value.
- Ignoring what happens when the term expires. Replacement coverage at 20 years older costs far more, and may not be available at any price. If the need outlives the term, the strategies are not equivalent at any return.
- Forgetting tax on the side fund. A 7% pre-tax return in a taxable account is not 7% after tax. The policy's inside build-up is tax-deferred, and the death benefit is tax-free.
- Comparing a policy against a side fund you would never hold. If you would keep the side fund in cash, compare the break-even return against a cash rate, not against an equity assumption.
Where the indexes come from
The interest-adjusted cost indexes are prescribed by the NAIC's Life Insurance Disclosure Model Regulation, adopted in most states, which requires insurers to furnish a buyer's guide and a policy summary containing the surrender cost index and the net payment cost index at 10 and 20 years, computed at 5% interest. They exist precisely because premium comparison and the traditional net cost method both mislead, and the disclosure requirement was the regulatory response. Ask for the disclosed figures on any policy you are quoted — they are computed by the insurer on the actual contract, including its real dividend scale, and they are a better input than anything you can reconstruct. Use this calculator to check them, to compare policies whose disclosures use different periods, and to see the break-even return the disclosure does not give you.
Deciding, once the numbers are in
The cost indexes rank policies. The break-even return prices the savings component. Neither answers whether you should own permanent insurance at all, and that question comes first.
If the need is temporary, term wins almost regardless of the arithmetic. Coverage that exists while a mortgage runs and children are dependent should expire when they do. Structuring it as a ladder tracks the declining exposure and costs less than one level policy. Buying permanent coverage for a temporary need means paying for a guarantee you will cancel.
If the need is permanent, the comparison changes shape. Estate liquidity on an illiquid business, a dependant with lifelong needs, a buy-sell agreement that has to fund whenever a partner dies — none of these can be met by a product that ends. For these the net payment cost index is the relevant one, and the break-even return is close to irrelevant, because the cash value is never realised.
If you are already in a policy, ask a different question. The money is spent and the acquisition costs are behind you. What matters now is the return the cash value earns from here, which is what the cash value return calculator measures, and whether the contract has become a modified endowment contract, which changes the tax on every loan and withdrawal.
Size the coverage before comparing products. The needs analysis gives the face amount a household can defend; the human life value method gives the amount an underwriter will justify. Buying a product that fits a premium budget rather than a face amount is the one mistake no cost index can detect.