Difficulty: Intermediate-Advanced | Prerequisites: Part 1 of these notes (pension plan types), time value of money (present value of ordinary annuities).
This section deals with the liability side of defined benefit pension plans: how the obligation is measured, how it changes from year to year, and how the plan's investment portfolio interacts with that obligation. This is where pension accounting gets genuinely difficult because the obligation involves projecting future cash flows decades out and discounting them back to the present. Actuaries do the heavy lifting, but you need to understand the three different ways the obligation is measured and why the PBO is the one used for financial reporting.
A defined benefit pension obligation can be measured three ways (ABO, VBO, PBO), each capturing a different slice of the liability. The PBO, which uses projected future salaries, is the measure used for balance-sheet reporting. The PBO changes each year due to five events: service cost, interest cost, prior service cost, gains/losses from estimate changes, and benefit payments. The funded status (plan assets minus PBO) determines whether the employer reports a net pension asset or liability.
Actuaries
Professionals who analyse the uncertainties in a defined benefit plan and provide the necessary estimated values. They use estimates of future salaries, life spans, personnel changes, and discount rates.
In simple terms, actuaries are the people who do the maths to figure out how much the company will owe its retirees.
Accumulated benefit obligation (ABO)
The present value of total retirement benefits earned to date by employees, using current salaries and actual years of service. It measures what the company would owe if the plan ended today.
Vested benefit obligation (VBO)
The present value of the vested portion of benefits earned by all employees, using current salary levels. It measures what the company must pay regardless of whether employees stay or leave.
Projected benefit obligation (PBO)
The present value of total retirement benefits earned to date, but calculated using projected future salaries rather than current salaries. This is the measure used for balance-sheet reporting of pension over- or underfunding.
Think of it as: the most forward-looking (and largest) measure of the obligation, because it factors in expected salary increases.
Vesting
The process by which an employee earns the right to keep employer contributions to their pension plan. Under ERISA, full vesting must occur within 7 years.
Service cost
The increase in the PBO due to employees earning an additional year of service.
Interest cost
The increase in the PBO because the liability is one year closer to payment. Calculated as the discount rate multiplied by the beginning-of-year PBO.
Prior service cost
The increase in PBO that results from retroactive amendments to the pension plan that grant additional benefits for past service.
Pension plan assets
The portfolio of investments (stocks, bonds, and other securities) held by a trustee to fund future pension payments. The balance changes with employer contributions, investment returns, and benefit payments to retirees.
Funded status
The difference between plan assets and the PBO. If plan assets exceed PBO, the plan is overfunded (net pension asset). If PBO exceeds plan assets, the plan is underfunded (net pension liability).
ERISA (Employee Retirement Income Security Act)
Federal legislation that establishes minimum funding requirements for pension plans and sets vesting schedules.
PBGC (Pension Benefit Guaranty Corporation)
A government agency that provides insurance to employees against underfunded defined benefit plans.
The company's pension obligation is the present value of the amounts it expects to pay out in future retirement benefits. Actuaries calculate this using estimates of future salaries, employee life spans, personnel changes, and a discount rate. There are three different ways to measure this obligation, and all three must be disclosed in the financial statement notes.
Accumulated Benefit Obligation (ABO)
Uses current salaries and actual years of service to date
Represents benefits employees have earned so far, discounted to present value
Useful measure of what the company would owe if the plan ended today
Example: Formula is 1.5% x years of service x final year's salary. An employee with 30 years of service and a current salary of $100,000 would have an ABO based on: 0.015 x 30 x $100,000 = $45,000 per year
Vested Benefit Obligation (VBO)
Measures only the vested portion of the ABO
An employee's right to employer contributions depends on vesting, which is the process of earning a non-forfeitable right to those contributions
Under ERISA, full vesting must occur within 7 years. A typical schedule: 20% after year 1, 40% after year 2, 60% after year 3, 80% after year 4, 100% after year 5
An employee's own contributions are always immediately vested
The VBO represents what the company must pay regardless of whether employees stay or leave
Example: If an employee has $6,300 in employer contributions and is 60% vested (3 years of service), the vested amount is $6,300 x 0.60 = $3,780
Projected Benefit Obligation (PBO)
Calculated the same way as the ABO, but using projected future salaries instead of current salaries
Incorporates estimates of salary increases, promotions, and other changes over the employee's remaining career
This is the measure used for reporting over- or underfunding of the pension on the balance sheet
Less objective than the ABO (because of the salary projections), but a better indicator of the true obligation because it accounts for expected future changes
PBO calculation example (Global Communications):
Jessica has worked for Global for 10 years. Her current salary is $100,000. The benefit formula is 1.5% x years of service x final year's salary. She is expected to retire in 2044 after 40 years of service, with a projected final salary of $400,000 and a 20-year retirement period. The discount rate is 6%.
Step 1: Calculate retirement benefits earned to date: 1.5% x 10 years x $400,000 = $60,000 per year (note: actual years of service to date, but projected salary)
Step 2: Calculate present value of the $60,000 annuity at the retirement date: PV of $60,000 for 20 years at 6% = $688,195
Step 3: Discount that amount back to today: PV of $688,195 discounted 30 years at 6% = $119,822
The PBO for Jessica at the end of 2014 is $119,822
The actual company PBO would aggregate this calculation across all employees.
The PBO varies from year to year due to five events:
1. Service cost
The additional benefits employees earn as another year of service elapses. Using the Global example, if Jessica completes year 11, her projected annual benefit rises from $60,000 to $66,000 (1.5% x 11 x $400,000), and the PBO increases accordingly.
2. Interest cost
The PBO grows each year because the liability is one year closer to being paid. This is the same concept as interest accruing on any liability. Interest cost = discount rate x beginning-of-year PBO.
For Jessica: the PBO goes from $119,822 to $139,715 in the next year, reflecting both the additional year of service and the one year less of discounting.
3. Prior service cost
When the pension plan formula is amended to provide higher benefits, the changes are often retroactive. Employees who already have years of service receive the enhanced benefits for those past years.
Example: If Global's formula changes from 1.5% to 1.7%, the retroactive increase for Jessica would change her projected annuity from $66,000 to $68,000, and the PBO would increase from $119,822 to $135,798. The prior service cost is the difference: $135,798 - $119,822 = $15,976.
4. Gain or loss on the PBO
When actuarial estimates change, the PBO is recalculated. An increase in the PBO from revised estimates is a loss (the company owes more). A decrease is a gain.
Common triggers for gains or losses:
Change in projected future salaries
Change in employee life expectancy
Change in expected retirement date
Change in the actuary's discount rate
Example: If projected salaries increase by an additional 5%, Jessica's final salary estimate rises from $400,000 to $420,000, increasing the future benefit and the PBO. This increase is a loss on the PBO.
5. Payment of retirement benefits
When the company pays benefits to current retirees, the PBO decreases. Part of the obligation has been fulfilled.
Annual PBO rollforward example ($ in millions):
Item | Amount |
|---|---|
PBO, beginning of 2016 | $400 |
+ Service cost | 41 |
+ Interest cost | 24 |
+ Loss on PBO | 23 |
- Retiree benefits paid | (38) |
PBO, end of 2016 | $450 |
Pension plan assets are the portfolio of investments held by a trustee (typically a bank or trust company) to fund future pension payments. The trustee is responsible for safekeeping, managing earnings, and making payments to retirees.
The balance in plan assets depends on three things:
Employer contributions (increases assets)
Investment returns earned over time (increases assets)
Retiree benefits paid out (decreases assets)
The amount the employer contributes each year is determined by actuarial analysis, based on expected returns and other factors.
Annual plan assets rollforward example ($ in millions):
Item | Amount |
|---|---|
Plan assets, beginning of 2016 | $300 |
+ Actual return on plan assets | 30 |
+ Cash contributions | 48 |
- Retiree benefits paid | (38) |
Plan assets, end of 2016 | $340 |
Funded status is the difference between plan assets and the PBO. This is what the employer reports on the balance sheet.
If plan assets > PBO, the plan is overfunded and the employer reports a net pension asset
If plan assets < PBO, the plan is underfunded and the employer reports a net pension liability
In the example above: PBO of $450 million minus plan assets of $340 million = $110 million net pension liability.
ERISA establishes minimum funding requirements to prevent severe underfunding. The PBGC provides a backstop of insurance for employees when plans are underfunded.
When you read a company's annual report and see a large "net pension liability" under long-term liabilities, that is the funded status at work. Companies with legacy defined benefit plans (airlines, automakers, steel companies) have often carried billions in net pension liabilities, which affects their credit ratings and borrowing costs. The funded status is also why some companies have frozen their defined benefit plans, stopping new benefit accruals, to limit the growth of the obligation.
Students often confuse the ABO and PBO. The ABO uses current salaries; the PBO uses projected future salaries. The PBO is always larger because it incorporates expected raises. The PBO is the one used for balance-sheet reporting.
A common error is thinking that the formula percentage (e.g. 1.5%) is something the actuary estimates. It is not. The formula is set by the plan itself and does not change unless the plan is amended.
Students sometimes assume that a gain on the PBO is good news for the company. Terminology here is counterintuitive: a "loss" on the PBO means the obligation increased (bad for the company), and a "gain" means it decreased (good for the company).
Another mistake is forgetting that benefit payments reduce both plan assets and the PBO simultaneously. The payment satisfies part of the obligation while also drawing down the investment pool.
⚠️ Be able to calculate the PBO for a single employee given the formula, projected salary, years of service, discount rate, and retirement period. This is a multi-step present value problem.
⚠️ Know all five events that change the PBO and their direction of effect (service cost increases PBO, interest cost increases PBO, prior service cost increases PBO, gains decrease PBO / losses increase PBO, benefit payments decrease PBO).
⚠️ Be able to construct a PBO rollforward from beginning to ending balance.
⚠️ Know how to determine funded status and whether the result is a net pension asset or net pension liability.
⚠️ Understand the difference between ABO, VBO, and PBO. Exam questions often ask which measure is used for a particular purpose.
True or false: The ABO uses projected future salaries. (False: the ABO uses current salaries. The PBO uses projected salaries.)
Fill in the blank: Under ERISA, full vesting must occur within ______ years. (7 years.)
True or false: An increase in the PBO due to revised actuarial estimates is called a "gain." (False: an increase in the obligation is a loss.)
Fill in the blank: Funded status = ______ minus ______. (Plan assets minus PBO.)
True or false: Benefit payments to retirees reduce the PBO but do not affect plan assets. (False: they reduce both.)
Q: When calculating a company's PBO, an actuary needs to estimate several parameters. Name one parameter that does not need to be estimated.
A: The percentage used in the company's formula for plan benefits (e.g. the 1.5% in "1.5% x years of service x final salary"). This is set by the plan itself.
Q: Service cost is one component of the PBO. What is service cost?
A: The added obligation due to an additional year of work by the employees. It reflects the increase in PBO because employees have earned one more year of service credit.
Q: After working at Number Crunchers LLC for one year, Carla is 20% vested in her employer's contributions to her 401(k). Her employer contributed $1,000 for the year. If Carla leaves now, how much of the employer's contributions stays in her account?
A: $200. Carla is 20% vested, so she keeps 20% of the $1,000 employer contribution. (Her own contributions are always 100% vested.)
Q: A company has a PBO of $450 million and plan assets of $340 million. What is the funded status, and how is it reported?
A: The funded status is $450M - $340M = $110 million net pension liability. Since the PBO exceeds plan assets, the plan is underfunded, and the company reports a net pension liability of $110 million on its balance sheet.
The PBO calculation builds directly on present value of annuity concepts from earlier chapters. The funded status ties into balance-sheet classification of long-term liabilities and assets. The five events that change the PBO feed directly into pension expense (covered in Part 3), where service cost, interest cost, and the other components become elements of the income statement.
PBO, projected benefit obligation, ABO, accumulated benefit obligation, VBO, vested benefit obligation, pension obligation, vesting schedule, ERISA, PBGC, service cost, interest cost, prior service cost, actuarial gain, actuarial loss, plan assets, funded status, overfunded, underfunded, net pension liability, net pension asset, pension plan rollforward, discount rate, ACCTG 472, Chapter 17