Investment Appraisal: Payback and ARR

Strategic decisions — whether to enter new markets, develop new products, or diversify — invariably require investment. Before committing resources, businesses need methods to evaluate whether a proposed investment is financially worthwhile. Investment appraisal provides the quantitative tools for making these decisions. This lesson covers the two simplest methods: payback period and average rate of return (ARR).

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What Is Investment Appraisal?

Investment appraisal is the process of evaluating whether a proposed capital investment is likely to generate sufficient returns to justify the cost. Capital investments typically involve large, upfront expenditures on assets such as:

• New machinery or equipment
• A new factory or store
• Launching a new product
• Entering a new market
• Acquiring another business

All investment appraisal methods compare the initial cost of the investment with the expected future returns (net cash flows) it will generate.

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Method 1: Payback Period

Definition

The payback period is the length of time it takes for an investment to generate enough net cash inflows to recover its initial cost. In other words, it answers the question: "How long until I get my money back?"

Calculation

To calculate payback, you add up the expected annual net cash flows until the cumulative total equals the initial investment.

Worked Example 1

A business invests £200,000 in a new production line. The expected net cash flows are:

Year	Annual Net Cash Flow (£)	Cumulative Cash Flow (£)
0	(200,000)	(200,000)
1	60,000	(140,000)
2	60,000	(80,000)
3	80,000	0
4	80,000	80,000
5	40,000	120,000

The cumulative cash flow reaches zero at the end of Year 3. Therefore, the payback period is 3 years.

Worked Example 2 (Payback During a Year)

A business invests £150,000. The expected net cash flows are:

Year	Annual Net Cash Flow (£)	Cumulative Cash Flow (£)
0	(150,000)	(150,000)
1	50,000	(100,000)
2	50,000	(50,000)
3	80,000	30,000

Payback occurs during Year 3. At the start of Year 3, £50,000 is still needed. Year 3 generates £80,000.

Payback = 2 years + (50,000 ÷ 80,000) × 12 months Payback = 2 years and 7.5 months

The formula for the partial year is:

Months in final year = (Amount still to recover ÷ Cash flow in that year) × 12

Advantages of Payback

Advantage	Explanation
Simple to calculate and understand	No complex mathematics — managers at all levels can use it
Focuses on cash flow	Cash flow is more objective than profit and harder to manipulate
Useful for cash-poor businesses	Firms with limited cash need to know when money will be returned
Reduces risk	Shorter payback = less time exposed to uncertainty; future cash flows are less predictable
Quick comparison	Easy to compare multiple projects — the one with the shortest payback returns funds fastest

Limitations of Payback

Limitation	Explanation
Ignores cash flows after payback	A project that pays back in 2 years but generates enormous returns in years 3–5 is treated the same as one that stops generating cash after payback
Ignores profitability	A project may pay back quickly but generate a low overall return on investment
Ignores the time value of money	£1 received today is worth more than £1 received in three years (due to inflation and opportunity cost) — payback treats them as equal
Arbitrary benchmark	There is no universally agreed "acceptable" payback period — the choice of cut-off is subjective
Encourages short-termism	May bias decisions towards quick-return projects and against long-term investments (e.g. R&D, infrastructure)

Exam Tip: When asked to calculate payback, always show your cumulative cash flow column clearly. If payback occurs during a year, you must show the fractional calculation. State your answer in years and months (not decimals). A common error is to forget that Year 0 represents the initial investment and is negative.

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