The Two Kings of Capital Budgeting: NPV and IRR
When you receive a lump-sum pension buyout offer from your employer, financial planners and actuaries use two primary metrics to analyze the offer: Net Present Value (NPV) and Internal Rate of Return (IRR).
While both formulas derive from discounted cash flow principles, they answer two fundamentally different questions.
1. What Question Does Pension NPV Answer?
NPV Question: "Given my assumed discount rate (e.g. 5.5%), what is the exact lump-sum dollar equivalent of this pension stream in today's money?"
NPV outputs a clear dollar amount (e.g. $485,000). If the calculated NPV is higher than the employer's buyout offer (e.g. $420,000), you know immediately that the monthly pension gives you a +$65,000 wealth advantage.
2. What Question Does Pension IRR Answer?
IRR Question: "What exact annual rate of return would I need to earn on the lump-sum offer to exactly match the monthly checks for the rest of my life?"
IRR outputs a percentage hurdle rate (e.g. 6.4%). If you know your personal investment portfolio only earns 4.5% safely, an IRR of 6.4% tells you that the pension is offering a return that you cannot replicate in the market without taking excessive risk.
Side-by-Side Comparison: NPV vs IRR
| Attribute | Net Present Value (NPV) | Internal Rate of Return (IRR) |
|---|---|---|
| Output Format | Absolute Dollar Value ($) | Percentage Rate of Return (%) |
| Requires Pre-set Discount Rate? | Yes (You input the rate) | No (Solves for the rate where NPV=0) |
| Primary Strength | Shows exact dollar gain or loss | Sets clear hurdle benchmark for investment advisors |
| Reinvestment Assumption | Assumes reinvestment at discount rate | Assumes reinvestment at the IRR itself (can distort) |
Which Metric Should You Use?
In professional actuarial practice, NPV is the preferred metric because it shows the exact dollar wealth difference and avoids the mathematical distortion of multiple internal rates of return. However, evaluating both metrics together gives you the complete picture.