Management Accounting · Asset budgeting and investment appraisal

Payback Period: Formula, Method and Exam Tips

Updated 11 October 2026 · Fact-checked

The payback period is the time a project takes to recover its initial investment from its cash inflows. With even cash flows, divide the initial investment by the annual cash flow. With uneven cash flows, add up cumulative cash flows year by year and find the point where they reach zero.

Understand Payback Period

Every investment starts with cash going out. The payback period asks one simple question: how long until that cash comes back?

It uses cash flows, not accounting profits. Depreciation is not a cash flow, so you ignore it. You also ignore sunk costs and non-cash items. You only use relevant future cash flows.

Managers set a target payback period. If a project pays back within that time, it is acceptable. If you compare projects, the one with the shorter payback is preferred. Payback is popular because it is simple and focuses on liquidity and risk. The sooner cash returns, the less time for things to go wrong.

Its weakness is that it ignores two things: the time value of money and all cash flows after the payback point. A project can pay back quickly but make little overall. Another can pay back slowly but be far more valuable. That is why payback is normally used alongside methods such as NPV.

Key formulas to remember

Payback period (even cash flows): Payback = Initial investment ÷ Annual net cash inflow; Use only when the inflows are the same each year. The answer is in years.
Payback period (uneven cash flows): Payback = Last full year before recovery + (Unrecovered cost at start of next year ÷ Cash flow in that year); Assumes cash flows arrive evenly through the year. Build a cumulative cash flow line first.
Decision rule: Accept if payback ≤ target payback; choose the shortest when comparing; Payback is a screening tool. It does not measure profitability.
Years to months: Months = Decimal part of a year × 12; For example, 0.5 years is 6 months.

How to solve Payback Period questions

Use this method for any payback question, whether the cash flows are even or uneven.

1List the initial investment at Year 0 as a negative cash flow.
2Write down the relevant net cash inflows for each year. Remove depreciation, sunk costs and other non-cash items.
3If the inflows are equal, divide the investment by the annual inflow and stop.
4If they are uneven, calculate the cumulative cash flow at the end of each year.
5Find the year in which the cumulative figure turns from negative to positive.
6Take the full years before that point, then add the unrecovered balance divided by that year's cash flow.
7Convert the decimal to months if the question asks for years and months.
8Compare with the target payback period and state whether the project is acceptable.

Quickest way: Cumulative cash flow line

When to use it: Use this for uneven cash flows in a multiple choice or number entry question where time is short.

Start with the investment as the amount still to recover.
Subtract each year's inflow in turn until the balance would go below zero.
Stop at the year where that happens. The balance left is the unrecovered amount.
Divide the unrecovered amount by that year's inflow and add to the full years.
Quickly check the answer lies between the two year numbers.

Common mistakes in Payback Period

Including depreciation as a cash outflow or deducting it from inflows.
Students use profit figures instead of cash figures.
Fix: Payback uses cash only. Add depreciation back if you start from profit, or ignore it if cash flows are given.
Dividing by the wrong year's cash flow when finding the fraction.
Students use the average or the previous year's inflow.
Fix: Divide the unrecovered balance by the cash flow of the year in which payback occurs.
Discounting the cash flows.
Confusion with NPV or discounted payback.
Fix: Simple payback uses undiscounted cash flows. Discount only if the question asks for discounted payback.
Using the even cash flow formula when the flows are uneven.
It is quick and looks familiar.
Fix: Check whether every year's inflow is the same. If not, use cumulative cash flows.
Saying a project is good just because payback is short.
Students forget that payback ignores cash flows after payback.
Fix: Describe payback as a measure of speed and risk, not of total return.
Giving the answer in the wrong units, such as 3.5 when 3 years 6 months is asked, or 3.6 years read as 3 years 6 months.
Decimals of a year are confused with months.
Fix: Multiply the decimal by 12. For example, 0.6 years is 7.2 months.

Worked examples

Example 1

A project costs $120,000 and produces net cash inflows of $30,000 each year for eight years. What is the payback period?

Show the solution

The inflows are even, so use the simple formula.
Payback = $120,000 ÷ $30,000.
Payback = 4 years.

Answer: 4 years

Example 2

A project needs an initial investment of $100,000. Net cash inflows are Year 1 $20,000, Year 2 $40,000, Year 3 $50,000, Year 4 $60,000. The target payback is 3 years. What is the payback period, and is the project acceptable?

Show the solution

Cumulative cash flow: Year 0 = -$100,000.
Year 1 = -$100,000 + $20,000 = -$80,000.
Year 2 = -$80,000 + $40,000 = -$40,000.
Year 3 = -$40,000 + $50,000 = +$10,000. Payback occurs during Year 3.
Unrecovered at start of Year 3 = $40,000. Year 3 inflow = $50,000.
Fraction = $40,000 ÷ $50,000 = 0.8 years.
Payback = 2 + 0.8 = 2.8 years, which is about 2 years 9.6 months.
2.8 years is less than the 3-year target.

Answer: Payback is 2.8 years. It is within the 3-year target, so the project is acceptable on this measure.

Exam tips

Check first whether cash flows are even or uneven. This decides the method in seconds.
In number entry questions, check the units asked for (years, months, decimals) and the decimal places required.
Advantages and limitations are common in multiple response questions. Remember: simple, favours liquidity and lower risk, but ignores time value of money, later cash flows and profitability.
Strip out depreciation and sunk costs before you start. Questions often include them as traps.
When asked which project to choose, remember payback alone is not enough. Mention that NPV is better for wealth maximisation.

Practice questions from Asset budgeting and investment appraisal

Payback Period in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Payback Period: frequently asked questions

What is the payback period formula for ACCA MA?

For even cash flows, payback equals the initial investment divided by the annual cash inflow. For uneven cash flows, find the year the cumulative cash flow turns positive. Then add the unrecovered balance divided by that year's cash flow to the full years before it.

How do you calculate payback with uneven cash flows?

Build a cumulative cash flow line from Year 0. Find the year in which the total moves from negative to positive. Payback is the number of full years before that, plus the unrecovered amount divided by that year's inflow.

What are the advantages and disadvantages of payback?

It is simple, easy to understand and highlights liquidity and risk, since quick recovery reduces uncertainty. However, it ignores the time value of money, ignores cash flows after payback and does not measure overall profitability.

Does payback use profit or cash flow?

It uses cash flow. Depreciation and other non-cash items are excluded. If you are given profits, add back depreciation to estimate the cash flow.