Principle-based reserving and what it means for prices

Principle-based reserving (PBR) is the method U.S. life insurers must use to calculate how much they set aside, called reserves, for life insurance policies issued on or after January 1, 2020. Instead of applying one fixed formula to every policy, PBR makes the insurer model the actual risks of the product it sold. Its effect on prices is indirect: it changes how much capital a company has to tie up, which can affect pricing decisions, but no one can point to a single premium change and attribute it to PBR.

What reserves are, and why the method matters

When you buy a policy, the insurer collects level premiums that, in the early years, exceed the cost of claims. The surplus is held as reserves to pay claims in later years when the cost of insurance rises. Reserves are a liability on the insurer's books, and the amount must be enough to keep the promise. Too low and the company may be unable to pay; too high and money is locked away that could support competitive pricing or earnings.

For most of the twentieth century, state law set reserves by formula: a prescribed mortality table, a prescribed interest rate, and rules that applied the same way to a 25-year-old nonsmoker and a 60-year-old with health issues. The formulas were simple and auditable but increasingly mismatched the products. Regulations adopted around 2000 for term life and for universal life with secondary guarantees produced reserves many insurers viewed as larger than the likely claims. Insurers responded by shifting business to captive and offshore reinsurers with different rules; see Offshore reinsurance and Bermuda: why it matters to policyholders.

How PBR works

The NAIC developed principle-based reserving in its Valuation Manual, Section VM-20 for life insurance. According to NAIC and actuarial sources, VM-20 became effective January 1, 2017 and became mandatory for new business issued on January 1, 2020 and later, with a three-year transition during which companies could elect to use it. Under VM-20, an insurer may have to calculate up to three amounts for each group of policies:

1. Net premium reserve (NPR). A formula-based floor using prescribed assumptions, in the spirit of the old method. It is the minimum reserve.
2. Deterministic reserve (DR). A projection, using the insurer's own best-estimate assumptions for mortality, lapses, expenses and investment returns plus a margin for uncertainty, of the policy's cash flows under a prescribed economic scenario.
3. Stochastic reserve (SR). A projection across many random interest-rate and market scenarios, with a cushion drawn from the worse outcomes.

The required reserve is the larger of the NPR and the results of the modeled approach. Products that are simple and well covered, or where the modeled reserve is shown to be less than the formula floor, can pass exclusion tests and use the NPR only, which saves insurers work. Mortality assumptions rest on company experience, credibility-weighted against industry tables such as the 2017 CSO table (see CSO mortality table). An actuary must certify the work, and the insurer's state of domicile examines it.

PBR also covers other products. VM-21 applies PBR to variable annuities, and VM-22 does the same for non-variable annuities, with a three-year transition that begins in 2026 and mandatory use for contracts issued from 2029, according to Milliman's 2024 description of the framework.

What it means for prices

The links from reserves to premiums run through several steps.

• Capital strain. If a method requires large reserves in the early years, the insurer has to commit more capital per policy. Companies price to earn a return on that capital, so lower redundant reserves can in principle support lower or steadier prices.
• Fit to the product. Because PBR responds to features like guaranteed premiums and lapse patterns, a company that has priced a product with bigger guarantees may hold more than before, and one with lighter guarantees may hold less. guaranteed universal life: permanent coverage without the cash is the clearest example, since its reserves depend on the guaranteed period and the lapse assumptions.
• Less reliance on captives. One goal was to reduce the incentive to use affiliated reinsurers purely for reserve relief. Whether it has done so is debated. Some regulators and analysts still point to affiliated reinsurance; the NAIC adopted separate asset adequacy testing for such reinsurance in 2025.
• Pricing is multi-factor. Mortality, interest rates, competition, expenses, sales volume and underwriting changes move premiums more visibly than reserving rules do. Read how life insurance premiums are calculated and mortality trends and how they move life insurance prices.

For you as a buyer, the practical effect is that reserving rules are one of the background reasons term and no-lapse products are priced and designed as they are, not a factor to compare among quotes.

A hypothetical illustration

Say an insurer sells a 20-year level term product. Under the old formula, it set reserves by a standard table and rate no matter how many policyholders it expected to drop coverage. Under PBR, its model might show that many buyers lapse in the first years and that its underwriting is stronger than the table assumed, so the modeled reserve is smaller than a purely formulaic one. The NPR floor still applies. The insurer might not cut premiums as a result, but the gap gives it pricing room. The numbers are invented to show the logic.

What to take from it as a consumer

1. PBR does not change your policy. Existing contracts, guarantees and premiums are unaffected.
2. Reserves are not the same as capital; read risk-based capital and life insurer solvency for how regulators set the extra cushion.
3. Do not choose a policy on reserving method. Compare AM Best, S&P, Moody's and Fitch ratings explained, the guarantees in the contract and the premium.
4. If you hold an older policy, its reserves were set under the earlier rules and remain valid.

Key takeaways

• PBR was effective January 1, 2017 and mandatory for new life insurance business from January 1, 2020; it asks insurers to model real risk rather than apply one formula.
• Insurers calculate a net premium reserve floor plus deterministic and stochastic modeled reserves unless exclusion tests apply.
• The effect on premiums is indirect, through capital and product design, and cannot be measured policy by policy.
• The reserving change does not alter existing contracts and is not a reason to choose or avoid a product.