Capital budgeting explained: this guide covers what it means, who it applies to, the step-by-step process, documents required, fees, due dates and penalties in India — so you can stay compliant with confidence and avoid costly mistakes.
A new machine or production line ties up money for years, so the owner needs a method that judges it on the cash it will bring and on when that cash arrives. Capital budgeting offers several tests. Some ignore the time value of money and are quick; others discount the cash flows and give a firmer answer. Owners, finance managers and anyone preparing a project for a lender should know all of them and the cases in which they disagree.
Estimate the extra, after-tax cash a project will bring each year, then test it. Payback = years to recover the outlay. Net present value (NPV) = present value of inflows - outlay, discounted at the firm's required return. Internal rate of return (IRR) is the discount rate at which NPV is zero. Profitability index = present value of inflows / outlay. Accept a project if its NPV is positive, that is, if IRR is above the required return and the index is above 1.
Estimating the cash flows
Most owners build this in a spreadsheet; a proper financial model keeps the cash flows, discount rate and results linked so that one changed assumption updates everything.
Use only incremental cash flows: what the firm will have with the project less what it would have without it. Include the following.
- The outlay on the asset, and any working capital that stock and debtors will need (recovered at the end).
- Extra sales less extra cash costs, after tax. Depreciation is not a cash cost, but it lowers tax, so add back the tax it saves. For the actual tax position, see our income-tax guides.
- The sale value of the asset at the end (salvage).
- Leave out sunk costs already spent and interest on the funds, which is covered by the discount rate.
The discount rate is the firm's required return, often its cost of capital adjusted for the project's risk.
The tests in order
| Test | Formula in words | Rule |
|---|---|---|
| Payback | Years until cumulative cash inflow equals outlay | Shorter is quicker, ignores later years |
| Accounting rate of return | Average annual profit over average investment | Compare with a target |
| NPV | Sum of (inflow x discount factor) less outlay | Accept if above zero |
| Profitability index | Present value of inflows over outlay | Accept if above 1 |
| IRR | Rate where NPV = 0, found by interpolation | Accept if above required return |
| Discounted payback | Payback using discounted inflows | Shorter is quicker, but includes timing |
The discount factor for year n at rate r is 1 / (1 + r)^n.
Worked example: Cascade Beverages' second line
Cascade Beverages is an invented bottling unit. A second line costs ₹80 lakh. It has a five-year life and an assumed salvage value of ₹8 lakh at the end of year 5. The estimated after-tax cash inflows, including the tax saved on depreciation at an assumed tax rate of 25 per cent, are ₹24, 26, 28, 26 and 24 lakh in years 1 to 5. The required return is assumed at 12 per cent. Discount factors are rounded to three decimals and present values to two.
| Year | Cash flow (₹ lakh) | Factor at 12% | Present value |
|---|---|---|---|
| 0 | -80 | 1.000 | -80.00 |
| 1 | 24 | 0.893 | 21.43 |
| 2 | 26 | 0.797 | 20.72 |
| 3 | 28 | 0.712 | 19.94 |
| 4 | 26 | 0.636 | 16.54 |
| 5 | 24 + 8 = 32 | 0.567 | 18.14 |
| Total inflows | 96.77 |
NPV = 96.77 - 80 = ₹16.77 lakh. It is positive, so the project beats the required return.
Profitability index = 96.77 / 80 = 1.21.
Payback. Cumulative inflow is 24, 50 and 78 after three years. The balance of 2 is recovered in year 4 of 26: 3 + 2/26 = 3.08 years. Salvage is not counted.
Discounted payback. Cumulative present value is 21.43, 42.15, 62.09 and 78.63 after four years. The balance of 1.37 comes from year 5's 18.14: 4 + 1.37/18.14 = 4.08 years.
Accounting rate of return. Depreciation is (80 - 8) / 5 = 14.4 a year. Total inflow is 128, less total depreciation of 72, leaves 56 of profit over five years, or 11.2 a year. Average investment = (80 + 8) / 2 = 44. ARR = 11.2 / 44 = 25.45 per cent. This uses cash inflow less depreciation as a rough measure of profit; in practice use the projected profit after tax.
IRR by interpolation. At 19 per cent the factors are 0.840, 0.706, 0.593, 0.499 and 0.419, and the present value of inflows is 20.16 + 18.36 + 16.60 + 12.97 + 13.41 = 81.50, an NPV of +1.50. At 20 per cent the factors are 0.833, 0.694, 0.579, 0.482 and 0.402, giving 19.99 + 18.04 + 16.21 + 12.53 + 12.86 = 79.64 (total taken from the unrounded values), an NPV of -0.36. IRR = 19 + 1.50 / (1.50 + 0.36) x (20 - 19) = 19 + 0.81 = about 19.8 per cent, comfortably above 12 per cent.
Decision. Cascade's owner approves the line: NPV is positive, the index is 1.21, IRR is near 19.8 per cent and the outlay comes back in about three years. Before signing, the owner tests the result against a fall in selling price; see risk in capital budgeting.
When NPV and IRR disagree
For a single project they agree. When two projects are alternatives, a smaller project with a higher IRR can have a lower NPV than a bigger one. Choose by NPV, as it shows the rupee gain. Disagreement also arises when cash flows change sign more than once. Then the modified rate of return, which assumes the inflows are reinvested at the required return, gives a single answer.
Capital rationing and unequal lives
When funds are limited, rank projects by profitability index and take them until the money runs out. When two machines have different lives, compare them on equal footing by spreading each cost over its life as an equivalent yearly figure, or by repeating them to a common horizon.
Common mistakes
- Including interest and then discounting too, which counts the cost of funds twice.
- Omitting working capital or its recovery.
- Counting sunk costs, or leaving out the tax saved on depreciation.
- Using payback alone, which ignores cash after the payback year.
- Choosing by IRR when projects are alternatives of different size.
- Using optimistic sales without testing a fall; the time value of money is explained in present value and future value.
Need help with a project appraisal?
If you are preparing an appraisal for a new line or a lender, our financial modeling service builds the cash flows, NPV and IRR on your assumptions and tests them under several cases. You get a model you can change as quotes and orders firm up.
Key takeaways
- Use incremental after-tax cash flows, including working capital and salvage.
- NPV is the main test: accept when positive.
- IRR and profitability index tell the same story for a single project.
- Payback is a quick liquidity check, not a measure of worth.
- Test the result against lower sales before deciding.
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Disclaimer: The methods described are standard cost accounting and financial management techniques. The worked example uses an invented business and invented figures, including any tax, interest or exchange rate, which are assumptions for illustration and not current rates. Where the article refers to a legal requirement, the linked guide and the official text should be checked. This article is general information, not legal advice; check the official text before acting.