What it means
A pension promise made today may be paid decades from now. The actuarial basis is what connects the two dates with numbers, because it states the assumptions about the future that the calculation relies on.
Four assumptions usually dominate pension work: the discount rate used to value future payments, the expected return on plan assets, salary growth and how long members live. Insurers use a similar set, with mortality, interest and expenses at the centre.
Together they form the basis for a given valuation. Each assumption moves the answer.
A higher discount rate shrinks the present value of the promise, and a higher expected asset return reduces the contribution needed today. That is why analysts read a company's pension assumptions as a test of management's prudence.
Aggressive assumptions flatter the present, and conservative ones cost more now but surprise less later. When reality differs from the basis, the difference is recorded as an actuarial gain or loss.
A run of losses is often the accounting signature of a plan drifting into deficit. Reporting rules also matter.
In the US, GASB Statement 67 covers financial reporting for public pension plans, while international groups apply IAS 19. The basis used for funding a plan and the basis used for accounting for it can differ, so check which one a number uses.
The basis is reviewed regularly because mortality, salaries and market returns drift. A manager reading an annual report should read the assumptions table slowly, since it says more about future cash demands than most headlines.
A plan is described as fully funded when its assets are enough to meet its obligations on the stated basis.
In practice
Real-world examples.
Example
A manufacturer assumes an 8% return on plan assets while markets deliver 5%. The flattering assumption keeps booked pension costs low for years, until a funding gap surfaces and required contributions jump.
Example
A city retirement system has its actuary update the basis each year: how long members will live, what they will earn and what the fund will return. The actuary then certifies the contribution the city must budget. When members live longer than assumed, the required contribution rises in the following year.
Example
An analyst comparing two rivals notices that one discounts its pension promises at 6.5% and the other at 5%. The first reports a smaller obligation for similar promises, which signals whose accounting is more optimistic. She adjusts both to the same rate before comparing their debt levels.
Formula
Calculation
Present value = future payment / (1 + discount rate)^years. Suppose a plan must pay $1,000,000 in 10 years. At a 5% discount rate, 1.05^10 is about 1.6289, so the present value is $1,000,000 / 1.6289, which is about $613,900. At a 7% discount rate, 1.07^10 is about 1.9672, so the present value is about $508,300. The same promise looks about $105,600 smaller on the 7% basis, which shows how one assumption alone changes the liability.Case study
Seen in the real world.
Dunmore Retail is a fictional chain used for this illustrative case study. Its CFO reviews the pension footnotes of an acquisition target before making an offer, and finds that the target assumes 8.5% asset returns and a high discount rate.
The CFO's actuaries re-run the numbers on a more cautious basis, which adds $40 million to the obligation. The offer price falls accordingly, and the deal closes with a funded top-up plan written into the agreement.
After completion, Dunmore adopts the cautious basis for the combined group and reports the change to its board. The board sees a larger but more honest liability, and later market swings surprise it less.
Watch out
Common mistakes.
- Treating the assumed return as a forecast; it is an accounting lever, and a high one quietly defers real cash costs.
- Reading the pension expense without the assumptions table; the same workforce can produce very different reported obligations under different discount rates.
- Assuming a fully funded plan stays funded; markets, salaries and longevity all move, so the valuation must be refreshed.
Questions
People also ask.
What are the key assumptions in an actuarial basis?
The discount rate, the expected return on plan assets, projected salary growth, mortality and employees' expected years of service. Small changes in any of them can move the reported obligation by large amounts.
Who sets the accounting rules?
In the US, GAAP governs private employers and GASB statements, such as Statement 67, govern public pension plans. Internationally, IAS 19 covers employee benefit accounting.
What does it mean for a plan to be fully funded?
Its assets are enough to meet the obligations to everyone currently owed benefits and everyone still earning them, measured on the stated basis. An actuarial valuation performs the test.
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