3. Decisions and Investment

Capital Budgeting

Discount incremental after-tax cash flows and expose forecast risk

Capital Budgeting

Long-lived projects commit cash before their benefits are known. The model must therefore capture timing, risk, reversibility and terminal effects.

Build cash flow, not accounting profit

Include:

  • equipment, installation and initial working capital;
  • incremental after-tax operating cash flows;
  • cannibalisation and opportunity costs;
  • later capital expenditure;
  • terminal disposal cash flow, tax and working-capital recovery.

Exclude:

  • sunk feasibility studies;
  • financing interest when the discount rate already reflects financing;
  • allocated costs that do not change.

Depreciation is non-cash, but it can affect tax cash flows. Northstar’s example supplies after-tax cash flows, so no separate tax shield is added.

Northstar automation case

  • equipment and installation now: £240,000;
  • working capital now: £20,000;
  • after-tax operating cash inflow: £75,000 at each year-end for four years;
  • year-4 salvage value: £20,000;
  • year-4 working-capital recovery: £20,000;
  • discount rate: 10%.
TimeCash flowExplanation
0−£260,000Equipment plus working capital
1+£75,000Operating
2+£75,000Operating
3+£75,000Operating
4+£115,000Operating + salvage + working-capital recovery
NPV=260,000+75,0001.10+75,0001.102+75,0001.103+115,0001.104=£5,060\text{NPV} = -260,000+ \frac{75,000}{1.10}+ \frac{75,000}{1.10^2}+ \frac{75,000}{1.10^3}+ \frac{115,000}{1.10^4} =£5,060

The project narrowly passes the 10% base case. Its approximate IRR is 10.84%; small forecast errors can reverse the decision.

Reproduce and stress-test

Py

Northstar NPV, IRR and rate sensitivity

Idle

Try reducing annual operating inflow by 5% or delaying year 1. A base-case recommendation should state which assumption has the lowest margin for error.

NPV, IRR and payback answer different questions

MethodUseful forMain limitation
NPVAbsolute value created at the chosen discount rateDepends on cash-flow and rate estimates
IRRPercentage-return communicationCan mis-rank mutually exclusive projects or produce multiple/no meaningful roots
PaybackLiquidity and exposure durationIgnores later cash; simple version ignores time value
Discounted paybackTime-adjusted recoveryStill ignores cash after recovery

When NPV and IRR conflict for mutually exclusive projects, NPV is normally the stronger value-creation rule if the discount rate and cash flows are well specified.

Risk is more than changing the rate

Separate:

  • sensitivity: one input changes;
  • scenario: coherent combinations such as weak demand plus high material cost;
  • simulation: distributions and dependencies across many outcomes;
  • real options: delay, expand, abandon or stage the project.

Do not hide operational uncertainty by adding an arbitrary percentage to the discount rate.

Post-investment review

After approval, preserve the original forecast and compare:

  • implementation spend and date;
  • realised volume, price, savings and working capital;
  • reasons for deviations;
  • benefits still achievable;
  • whether to continue, redesign or stop.

The purpose is learning and corrective action, not rewriting the business case to appear correct.

Quick check

Why is recovering £20,000 working capital in year 4 a cash inflow even though it is not revenue?

Answer
The project releases cash previously tied up in operating assets. Revenue recognition and project cash flow are different classifications.

Next: Northstar Capstone

Copyright © 2026