IAI Actuarial Core Principles · Business Finance

Personal and Corporate Taxation for IAI CB1

Personal and corporate taxation covers how governments tax individuals and companies, and how those taxes change investment and financing decisions. To solve questions, identify the tax type, find the taxable amount after allowable deductions, apply the rate, then compare after-tax cash flows or costs. State your assumptions clearly.

What this chapter covers

This chapter in Business Finance (CB1) explains how tax works and why it matters to financial decisions. You start with the principles of a good tax system and the main types of tax: direct and indirect, progressive, proportional and regressive. Then you move to how individuals are taxed on income and capital gains, and how companies are taxed on their taxable profit.

The key idea is that tax is a cash outflow, and it is not applied to accounting profit directly. Taxable profit is accounting profit adjusted for items the tax law treats differently, such as depreciation versus capital allowances. Interest is usually deductible for companies, while dividends are paid out of profit after tax. This difference drives much of the later material.

The chapter connects to the rest of the paper in three places. It feeds into how corporates are financed, because the tax shield on debt affects the cost of debt and the choice of capital structure. It feeds into evaluating projects, because cash flows should be taken after tax. It also links to company accounts, where tax charges and deferred tax appear. Study the principles in general terms. Use the rates and rules given in the question or the IAI study material, and do not rely on memory of current rates unless the question requires it.

Tax is rarely tested as an isolated topic. It appears inside financing, cost of capital and project appraisal questions, so a weak grasp costs marks in the heaviest parts of the paper, such as how corporates are financed and company accounts. Learning the logic once lets you handle both short multiple-choice questions and longer written questions on after-tax cash flows, the debt tax shield and the effect of tax on investor returns. The calculations are simple. Marks are lost on method and on stating assumptions, so this chapter rewards steady practice.

Personal and corporate taxation: topics in the order to study them

1Principles of Taxation and Types of TaxStart here because the vocabulary of direct and indirect tax, tax bases and tax rate structures is used in every later topic.
2Personal Income Tax and Capital GainsNext, because individual investors are the ones who receive dividends, interest and gains, and you need their position to see how tax affects investor returns.
3Corporate Taxation and Taxable ProfitStudy this after personal tax so you can contrast how a company is taxed and learn to move from accounting profit to taxable profit.
4Tax Effects on Financing and Capital StructureFinish with this topic because it combines everything: it needs corporate tax, investor tax and the difference between debt and equity.

How to prepare Personal and corporate taxation

Aim to understand the logic first, then practise turning it into short, clear working. Use the rates and rules in the question or your IAI study material.

Read the principles of taxation and write a one-line definition of each tax type and rate structure in your own words.
Practise a simple income tax calculation: gross income, less allowable deductions, taxable income, tax at the given rates, then net income.
Work through corporate examples that start with accounting profit and adjust to taxable profit, noting which items are added back and which are deducted.
Calculate the debt tax shield as interest × tax rate, and compare the after-tax cost of debt with the cost of equity.
Redo one project appraisal question with and without tax so you see how after-tax cash flows change the result.
Write short answers on why tax favours debt and what limits its use, such as financial distress costs, and practise stating assumptions.
Finish with timed multiple-choice questions, then one written question, and check that you show method, working and result.

Common mistakes in Personal and corporate taxation

Applying the tax rate to accounting profit instead of taxable profit.
Fix: Always check for depreciation, capital allowances and non-deductible items before applying the rate.
Treating dividends as tax deductible for the company.
Fix: Remember that interest is deducted before tax, while dividends are paid out of profit after tax.
Using the pre-tax cost of debt in cost of capital calculations.
Fix: Multiply by (1 − tax rate) when interest is deductible and the company is paying tax.
Claiming a tax shield when the company has no taxable profit.
Fix: State the assumption that profits are sufficient, or explain the effect of losses.
Mixing up progressive, proportional and regressive taxes.
Fix: Attach a simple numerical example to each type and check whether the share of income paid rises, stays flat or falls.
Giving a numerical answer with no stated assumptions or method.
Fix: Write the formula, the rate used, the working and the final answer with a short note on assumptions.

Last-day revision: Personal and corporate taxation

Direct tax is levied on income or wealth of the person who pays it; indirect tax is levied on spending and passed on.
Progressive tax takes a rising share as income rises; proportional takes a constant share; regressive takes a falling share.
Good tax principles include certainty, fairness, convenience and economy of collection.
Taxable income = gross income − allowable deductions and reliefs.
Capital gain = sale proceeds − cost (after allowable costs); apply the gains rules given in the question.
Taxable profit differs from accounting profit because tax law treats depreciation and some expenses differently.
Interest is generally tax deductible for companies; dividends are paid from profit after tax.
Debt tax shield = interest × corporate tax rate, assuming the company has enough profit to use it.
After-tax cost of debt = pre-tax cost of debt × (1 − tax rate).
Use after-tax cash flows in project appraisal.
Tax can favour debt, but financial distress costs limit how much debt is sensible.
Always state your assumptions, such as the tax rate and timing of tax payment.

Personal and corporate taxation practice questions

Personal and corporate taxation in other exams

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

Personal and corporate taxation: frequently asked questions

Which IAI subject covers personal and corporate taxation?

This chapter sits in Business Finance, CB1, one of the Business subjects in the Core Principles stage. It links to corporate financing, project appraisal and company accounts.

Do I need to memorise current tax rates?

Not as a rule. Questions normally give the rates or the rules to apply. Focus on the method, the logic and the effect of tax on financial decisions, and check the IAI study material for what is expected.

How is tax tested in the CB1 paper?

It can appear in multiple-choice questions on definitions and simple calculations, and in written questions on after-tax cash flows, the cost of debt and capital structure. Show your working and assumptions in written answers.

Why does tax matter for capital structure?

Interest is usually deductible, so debt lowers the tax a company pays and reduces its after-tax cost of borrowing. This pushes companies towards debt, but the risk of financial distress limits how far it makes sense to go.

What is the best way to revise this chapter quickly?

Go through the quick revision points, then do one tax calculation from gross income to net income and one after-tax cost of debt example. Finish with a few timed multiple-choice questions.