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Discounted cash flow: NPV, annuities and perpetuities

ICAN Professional, Strategic Financial Management. Syllabus area B, advanced investment appraisal

11 min read · Updated 8 November 2026

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A company can spend ₦800m on a new plant today and receive cash over the next four years. Is it a good deal? Adding up the cash is not enough, because ₦100 received in three years is worth less than ₦100 today. A bank pays interest, so money in hand can earn.

Discounted cash flow (DCF) puts every cash flow on the same date, today, so that costs and benefits can be compared fairly.

This topic covers capital expenditure and investment appraisal, the time value of money, discounting and discount tables, the net present value (NPV) method, working capital in a project, annuities and perpetuities (including growing ones), and uses of annuity arithmetic: equivalent annual costs, loan repayments and sinking funds. The previous area covered governance. The next topic covers the internal rate of return, the modified internal rate of return and relevant costs.

The May 2014 and November 2014 Pathfinder papers tested NPV inside larger project questions.

In 30 seconds

A sum today is worth more than the same sum later, so future cash flows are discounted at the cost of capital: discount factor = 1 ÷ (1 + r)n. NPV is the present value of inflows less the present value of outflows. Accept if NPV is positive, because the project adds value. Cash flows are placed at year ends, with “time 0” as now.

Include working capital as an outflow at the start and an inflow at the end. An annuity is a constant cash flow for a set number of years, with annuity factor = [1 − (1 + r)−n] ÷ r. A perpetuity is a constant flow forever: PV = cash flow ÷ r. With constant growth g, PV = first cash flow ÷ (r − g).

Key terms in plain English

TermWhat it means
Capital expenditureSpending on non-current assets or a new business that lasts several years
Investment appraisalJudging whether a capital project is worth doing
DiscountingTurning a future amount into its equivalent today
Cost of capitalThe return investors require, used as the discount rate
Net present value (NPV)PV of inflows minus PV of outflows
AnnuityA constant cash flow each year for a fixed number of years
PerpetuityA constant cash flow each year forever
Sinking fundEqual yearly savings that build up to a target amount

Syllabus check

This topic is in syllabus area B (advanced investment appraisal, 30% of the marks, the largest area). It covers:

  • the time value of money and discounted cash flow;
  • net present value and its decision rule;
  • annuities, perpetuities and their uses in appraisal.

CAMA 2020 and investment appraisal

The Companies and Allied Matters Act 2020 (CAMA 2020) is the company law of Nigeria. The sections below apply to this topic.

The Companies and Allied Matters Act 2020 (CAMA 2020) is the company law of Nigeria.

SectionWhat it saysLink to this topic
s. 305A director must act in good faith in the best interests of the companyProjects and decisions should add value to the company
s. 308A director must use the care, diligence and skill of a reasonably prudent directorDirectors should test the assumptions behind a decision
s. 377(1) and s. 378Directors prepare statements that follow IFRS and give a true and fair viewDecisions later affect reported assets, profit and cash
s. 385The directors’ report covers performance and riskMajor plans and risks are reported to shareholders

Capital expenditure and appraisal

Capital expenditure is spending on non-current assets such as buildings and equipment, or on a new business, that appears on the statement of financial position. Revenue expenditure is written off as an expense or creates a short-term asset such as inventory. Capital projects may be essential (replacing worn-out assets) or discretionary (new business that should earn a return). Examination questions mostly concern discretionary spending.

Investment appraisal evaluates proposals. A project should be undertaken only if it gives a suitable financial return and the risk is acceptable. Appraisal sits inside a capital budget, often a five-year plan reviewed each year, with approved projects inside spending limits. The steps are: generate proposals that match strategy; forecast relevant cash flows; evaluate; implement those that meet the criteria; and monitor performance against expectations.

Typical projects involve a large payment at the start, returns over several years, a possible residual value at the end and an investment in working capital. A project to buy a business has an initial outlay and possibly returns over a very long period.

The time value of money

A sum today is worth more than the same sum later, because it can be invested to earn a return. Two techniques deal with this:

  • Compounding finds the future value of a sum invested at an interest rate.
  • Discounting finds the present value (PV) of a future sum. It is the reverse of compounding.

Discount factor = 1 ÷ (1 + r)n, where r is the interest or cost of capital per period and n the number of periods. PV = future amount × discount factor. The present value is the sum that, invested today, would grow to the future amount, so an investor is indifferent between them. Discount tables list factors by rate and year. For example, at 10%: year 1, 0.909; year 2, 0.826; year 3, 0.751; year 4, 0.683.

Net present value

DCF has two forms, NPV and the internal rate of return (IRR). For NPV:

  1. List all cash flows: the initial investment, future inflows and outflows.
  2. Discount them at the company’s cost of capital.
  3. NPV = PV of benefits − PV of costs. Accept if NPV is positive. Reject if negative.

Cash flows are assumed to arise at the end of each year. “Year 0” (time 0) is now, year 1 is the end of the first year, and so on. Using NPV is consistent with the aim of maximising shareholders’ wealth, because a positive NPV is the amount by which the project should add to the value of the company.

Layouts

Format 1 lists each item with its factor. Format 2 sets out years across and nets the cash flows for each year, which saves discounting repeatedly when there are many items. Changes in working capital are cash flows. An increase, usually at the start, is an outflow. The investment is released (an inflow) at the end of the project, so working capital ends at zero.

Layout example. Machine ₦40,000, working capital ₦5,000, cash profits ₦20,000 a year for 3 years, sale of the machine ₦6,000 and recovery of working capital in year 3. Cost of capital 10%.

YearItemCash flow ₦Factor at 10%PV ₦
0Machine(40,000)1.000(40,000)
0Working capital(5,000)1.000(5,000)
1 to 3Cash profits20,0002.48749,740
3Sale of machine6,0000.7514,506
3Recovery of working capital5,0000.7513,755
NPV13,001

The NPV is positive, so the project is accepted.

Annuities and perpetuities

An annuity is a constant cash flow for a set number of years, for example ₦30,000 a year for years 1 to 5. Its present value is the cash flow times the annuity factor, which is the sum of the individual discount factors. The formula is [1 − (1 + r)−n] ÷ r. A table gives the same result. At 9%, years 1 to 3: 0.917 + 0.842 + 0.772 = 2.531. So ₦50,000 a year for three years has a PV of 50,000 × 2.531 = ₦126,550.

A perpetuity is a constant flow for ever. Perpetuity factor = 1 ÷ r. A cash flow of ₦2,000 a year from year 1 at 8% has a PV of 2,000 ÷ 0.08 = ₦25,000.

Growth

If the flow grows at a constant rate g, the growing annuity has PV = [CF1 ÷ (r − g)] × [1 − ((1 + g) ÷ (1 + r))n], where CF1 is the first cash flow. The growing perpetuity has PV = CF1 ÷ (r − g), which needs r greater than g.

Using annuity arithmetic in reverse

  • Equivalent annual cash flow or cost: divide a present value by the annuity factor.
    The minimum yearly return needed from a ₦70,000 project over 5 years at 9% is 70,000 ÷ 3.890 = ₦17,995.
  • Loan repayments: divide the amount borrowed by the annuity factor.
    ₦10,000,000 repaid in 5 equal yearly payments at 8% is 10,000,000 ÷ 3.993 = ₦2,504,383.
  • Sinking fund: equal yearly savings that reach a target. The sinking fund factor is [(1 + r)n − 1] ÷ r. To save ₦5,000,000 over 10 years at 6%, the factor is about 13.181, so the yearly saving is about ₦379,340.

The rules in more depth

Why the cost of capital is the discount rate

It is the return investors could get elsewhere at the same risk. A project must beat it to add value.

Why year-end timing is a simplification

Real cash flows arise throughout the year. The convention keeps the arithmetic simple. If a question puts a cash flow early in a year, it is usually treated as the end of the previous year.

Why NPV is an absolute measure

It gives the money value added, so a large project with a large NPV can be ranked above a small project with a higher percentage return.

Why financing costs are left out

Interest and loan repayments are in the discount rate. Counting them in the cash flows would count them twice.

Effect on analysis

List the cash flows by year and net them. Discount at the right rate. State the decision and any risk or non-financial factor that might change it.

Worked examples

Example 1: comparing cash flows over time. A borrower owes ₦120,000 in 3 years. He offers ₦140,000 if he can repay in 5 years. The lender can earn 7%.

  1. PV of the existing contract.
    120,000 ÷ 1.073 = ₦97,955.
  2. PV of the offer.
    140,000 ÷ 1.075 = ₦99,816.
  3. The offer has the higher PV, so it is acceptable.

Example 2: a simple NPV. A project costs ₦10,000 now and returns ₦6,000 in year 1 and ₦8,000 in year 2. Cost of capital 10%.

  1. PV of year 1 = 6,000 × 0.909 = ₦5,454.
  2. PV of year 2 = 8,000 × 0.826 = ₦6,608.
  3. NPV = 5,454 + 6,608 − 10,000 = ₦2,062.
    Accept.

Example 3: a growing annuity. A receipt of ₦50,000 in today’s money grows at 10% a year for 5 years. Cost of capital 15%.

  1. First cash flow.
    50,000 × 1.10 = ₦55,000.
  2. PV = [55,000 ÷ (0.15 − 0.10)] × [1 − (1.10 ÷ 1.15)5] = 1,100,000 × (1 − 0.8006).
  3. PV is about ₦219,300. A year-by-year table with rounded factors gives ₦219,221, the difference being rounding.

Example 4: a loan repayment. A company borrows ₦20m, repayable in 4 equal yearly instalments at 10%.

  1. Annuity factor, 10%, 4 years = 3.170.
  2. Instalment = 20,000,000 ÷ 3.170 = ₦6,309,148.
  3. Total repaid.
    4 × 6,309,148 = ₦25,236,592, so interest = about ₦5.24m.

How to score full marks

  • Set out the cash flows by year in a table.
  • Use the right factor and show the rate.
  • Include working capital and its recovery.
  • Leave out financing costs, depreciation and sunk costs.
  • State the decision and the reason.
  • Check that the signs are right and that annuities start in the right year.

Common mistakes in the exam

  • Discounting depreciation, which is not a cash flow.
  • Using the annuity factor for the wrong start year.
  • Forgetting to release working capital at the end.
  • Including interest in the cash flows as well as in the rate.
  • Using the perpetuity formula when growth is higher than the rate.
  • Giving a number without a recommendation.

Quick revision

  • Discount factor = 1 ÷ (1 + r)n. NPV positive: accept.
  • Annuity factor = [1 − (1 + r)−n] ÷ r.
    Perpetuity = CF ÷ r.
    Growing perpetuity = CF1 ÷ (r − g).
  • Working capital: out at the start, back at the end.
  • Equivalent annual cash flow, loan repayment and sinking fund use annuity factors in reverse.
  • CAMA 2020: ss. 305, 308, 377(1), 378, 385.

Practice questions

These are original questions written in the style of the Institute of Chartered Accountants of Nigeria (ICAN) exam. Try each one before you open the answer. Full model answers follow the written questions.

Recall check: multiple choice

Recent ICAN papers are written, although older papers such as May 2014 included multiple-choice questions. These questions are for quick recall. The written questions that follow are closer to the exam.

Question 1. A sum received in the future is worth:

  1. More than the same sum today
  2. Less than the same sum today
  3. The same as today
  4. Nothing
Show the answer

B. Because money today can earn a return.

Question 2. The discount factor for year n is:

  1. 1 ÷ (1 + r)^n
  2. (1 + r)^n
  3. r ÷ n
  4. 1 − r
Show the answer

A. The inverse of the compound factor.

Question 3. A project should be accepted when its NPV is:

  1. Negative
  2. Zero only
  3. Positive
  4. Below the IRR
Show the answer

C. It adds value.

Question 4. Which item is NOT included in NPV cash flows?

  1. Working capital
  2. Depreciation
  3. Scrap value
  4. Cash profits
Show the answer

B. It is not a cash flow.

Question 5. Working capital in a project is usually:

  1. An inflow at the start
  2. An outflow at the start and an inflow at the end
  3. Ignored
  4. Depreciated
Show the answer

B. It is released at the end.

Question 6. The PV of a perpetuity of ₦2,000 at 8% is:

  1. ₦16,000
  2. ₦25,000
  3. ₦2,160
  4. ₦250
Show the answer

B. 2,000 ÷ 0.08.

Question 7. A growing perpetuity has PV equal to:

  1. CF1 ÷ (r − g)
  2. CF1 ÷ r
  3. CF1 × r
  4. CF1 × (1 + g)
Show the answer

A. Provided r is greater than g.

Question 8. To find the equivalent annual cost, divide the PV by:

  1. The discount factor
  2. The annuity factor
  3. The perpetuity factor
  4. The tax rate
Show the answer

B. For the same period and rate.

Question 9. Interest on a project loan should be:

  1. Included in the cash flows
  2. Left out of the cash flows, because it is in the discount rate
  3. Discounted twice
  4. Deducted from NPV
Show the answer

B. Otherwise it is counted twice.

Question 10. Which section of CAMA 2020 sets the director’s duty of care and skill?

  1. Section 308
  2. Section 400
  3. Section 405
  4. Section 409
Show the answer

A. Directors should test the assumptions in an appraisal.

Written questions

Question 11 (10 marks). (a) Explain why future cash flows are discounted. (3 marks) (b) State the steps in an NPV appraisal and the decision rule. (4 marks) (c) State the treatment of working capital in an NPV calculation. (3 marks)

Question 12 (20 marks). Biso Plc is considering a plant costing ₦800m. It needs working capital of ₦100m at the start, which is recovered at the end of year 4. Cash profits are ₦300m a year for years 1 to 4, and the plant can be sold for ₦50m at the end of year 4. The cost of capital is 12% (annuity factor for 4 years 3.037, discount factor for year 4 0.636).

(a) Calculate the NPV and advise. (8 marks) (b) The company wants to borrow ₦50m, repaid in 5 equal yearly instalments at 10% (annuity factor 3.791). Calculate the instalment. (4 marks) (c) A property will pay ₦24m a year for ever. Calculate its value at 8%. (3 marks) (d) Explain why interest is not included in the project cash flows. (5 marks)

Question 13 (10 marks). (a) A company expects dividends of ₦20m next year, growing at 5% a year for ever. Calculate the present value at 13%. (4 marks) (b) Explain the difference between an annuity and a perpetuity and give a use of each in appraisal. (6 marks)

Model answers

Show the model answer to Question 11

(a) Why discount (3 marks). A sum today can be invested to earn a return, so it is worth more than the same sum later. (1.5) Discounting puts all cash flows on the same date so that they can be compared. (1.5)

(b) Steps and rule (4 marks). List all cash flows. (1) Discount them at the cost of capital. (1) Subtract the PV of costs from the PV of benefits. (1) Accept if NPV is positive and reject if negative. (1)

(c) Working capital (3 marks). The investment is an outflow, usually at the start. (1.5) It is released as an inflow at the end, so the balance returns to nil. (1.5)

Show the model answer to Question 12

(a) NPV (8 marks).

  1. PV of cash profits.
    300 × 3.037 = ₦911.1m. (2)
  2. PV of sale.
    50 × 0.636 = ₦31.8m. (1.5)
  3. PV of working capital recovered.
    100 × 0.636 = ₦63.6m. (1.5)
  4. Outflows = 800 + 100 = ₦900m. (1)
  5. NPV = 911.1 + 31.8 + 63.6 − 900 = ₦106.5m. (1)
  6. It is positive, so accept. (1)

(b) Instalment (4 marks). 50m ÷ 3.791 = ₦13.19m a year. (4)

(c) Perpetuity (3 marks). 24 ÷ 0.08 = ₦300m. (3)

(d) Interest (5 marks). The cost of capital already reflects the return that lenders and shareholders require. (2.5) Counting interest in the cash flows as well would count the cost of finance twice and understate NPV. (2.5)

Show the model answer to Question 13

(a) Growing perpetuity (4 marks). PV = 20 ÷ (0.13 − 0.05) = 20 ÷ 0.08 = ₦250m. (4)

(b) Annuity and perpetuity (6 marks). An annuity is a constant cash flow for a fixed number of years, and a perpetuity is a constant flow for ever. (2) Annuity use: yearly cash profits over a project life, or a loan repayment. (2) Perpetuity use: valuing a long-lived income stream or a share with constant dividends. (2)

Pathfinder on NPV, annuities and perpetuities

These are the ICAN Pathfinder questions that test this topic. ICAN owns the questions and the suggested solutions, so we point you to them and do not copy them. Open your Pathfinder, attempt each question under exam conditions, then check your answer against the notes above.

November 2014 Pathfinder, question 1

The compulsory 30-mark question asked for a project NPV for a cement plant at a project-specific cost of capital of 13%. The model answer lists the cash flows by year, takes tax on operating profit, adds the tax saving on tax depreciation, includes working capital at 10% of revenue as an outflow at the start of each year and a recovery at the end, and leaves out loan repayments, interest, apportioned overheads and sunk survey costs. Worked example 2 and the layout table show the same method on smaller numbers.

Revise first: Net present value

Annuity arithmetic

Questions use annuity factors for equivalent annual costs, loan repayments and sinking funds. See the section on annuities and perpetuities.

Revise first: Annuities and perpetuities

Source: ICAN Pathfinder, Strategic Financial Management. Diets covered: November 2014 question 1 and May 2014 question 1 (NPV inside larger questions).

Spotted a mistake? Tell us and we will check it.

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See every past question on Strategic Financial Management and the topic each one tests in the Pathfinder question finder.

This course builds on Financial Management and Performance Management. After it, move on to Case Study.

All Strategic Financial Management topics

You are reading topic 24 of 71.

  1. Strategic financial management and corporate objectives01
  2. The treasury function02
  3. Stakeholders, corporate social responsibility and ethics in financial management03
  4. Money laundering and the duties of directors04
  5. The economic environment, free trade and international institutions05
  6. Government influence on business and the financial management framework06
  7. Financial markets, money markets and money market instruments07
  8. Dividend policy, dividend capacity and transfer pricing08
  9. Emerging issues: the financial crisis, dark pools and new asset classes09
  10. Technology tools for financial management10
  11. Strategic analysis: PESTEL, SWOT and the five forces11
  12. The Ansoff matrix and methods of strategic development12
  13. Assessment and selection of business strategies13
  14. Business plans and communicating strategy14
  15. Strategic change and managing change15
  16. Risk, risk management and categories of risk16
  17. Identification, assessment and measurement of risk17
  18. Monitoring and controlling risk, and enterprise risk management18
  19. Corporate governance: meaning, concepts and stakeholders19
  20. Agency theory and other governance theories20
  21. Governance codes: rules-based and principles-based approaches21
  22. The board: roles, composition and committees22
  23. Directors and the law, director development and audit23
  24. Discounted cash flow (i): NPV, annuities and perpetuities24 here
  25. Discounted cash flow (ii): IRR, MIRR and relevant costs25
  26. Discounted cash flow (iii): taxation and capital allowances26
  27. Discounted cash flow (iv): inflation27
  28. Risk and uncertainty (i): sensitivity analysis and expected values28
  29. Risk and uncertainty (ii): decision trees, risk-adjusted rates and other methods29
  30. The lease versus buy decision30
  31. Asset replacement decisions31
  32. Capital rationing32
  33. Cost of capital and the weighted average cost of capital33
  34. Risk, return and portfolio theory34
  35. The capital asset pricing model and the cost of capital for appraisal35
  36. Sources of finance: equity and rights issues36
  37. Sources of finance: debt, convertibles and preference shares37
  38. Finance for SMEs and venture capital38
  39. Islamic finance39
  40. Financing projects and capital structure theories40
  41. Gearing, WACC and asset and equity betas41
  42. Adjusted present value42
  43. International Valuation Standards43
  44. Business valuation: asset-based and income-based methods44
  45. Dividend valuation models45
  46. The valuation of debt and preference shares46
  47. The efficient market hypothesis47
  48. Value-based management: EVA and MVA48
  49. Cash flow valuation and free cash flow49
  50. International investment decisions50
  51. Option pricing theory and the Black-Scholes model51
  52. Real options and applications of Black-Scholes52
  53. Mergers and acquisitions: strategic and regulatory issues53
  54. Valuation for mergers and acquisitions54
  55. Financing acquisitions and mergers55
  56. Capital reconstructions56
  57. Business reorganisation and management buyouts (MBO)57
  58. Forecast financial statements58
  59. Evaluating financial performance, position and proposed strategies59
  60. Corporate failure and how to predict it60
  61. Foreign exchange rates and exposure61
  62. Exchange rate relationships: PPP and interest rate parity62
  63. Forward contracts, money market hedges and netting63
  64. Duration and convexity64
  65. Yield curves and credit risk65
  66. Forward rate agreements and interest rate swaps66
  67. Forward rates from yield curves and currency swaps67
  68. Futures and hedging with futures68
  69. Currency futures and short-term interest rate futures69
  70. Hedging with options, caps, floors and collars70
  71. Delta hedging and the Greeks71
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