Company Income Tax (CIT) is charged on assessable profit, not raw revenue. Every properly documented, allowable deduction reduces that profit figure, and by extension, the tax due. Many businesses, particularly smaller ones without a dedicated finance function, understate their deductions simply because expenses were not properly recorded or claimed. This article outlines the general test for deductibility and areas that are commonly missed.
How it works
Under the general principle carried through Nigerian tax law, and consistent with the Nigeria Tax Act, 2025, an expense is deductible if it is incurred wholly, exclusively, necessarily and reasonably for the purposes of the business. Each word matters:
- Wholly — the entire expense relates to the business, not partly to personal use.
- Exclusively — the expense was incurred only for business purposes.
- Necessarily — the expense was required for carrying on the business.
- Reasonably — the amount incurred is proportionate to the business need.
An expense that fails any part of this test may be disallowed, in whole or in part, when computing taxable profit.
Deductions commonly overlooked
- Professional and consulting fees — accounting, legal, tax advisory and audit fees incurred for the business.
- Bank charges and transaction fees on business accounts.
- Staff training costs directly related to the business.
- Repairs and maintenance of business equipment and premises (as distinct from capital improvements, which are typically treated as capital expenditure and dealt with through capital allowances rather than direct deduction).
- Rent paid for business premises.
- Utility costs attributable to business operations.
- Insurance premiums on business assets and liabilities.
- Bad debts written off, where they meet the conditions for deductibility.
- Pension and statutory contributions made by the employer for staff.
- Advertising and marketing costs.
Why this matters to taxpayers
Under-claiming allowable expenses results in an overstated profit figure and, consequently, a higher tax liability than is actually due. This is a common outcome where a business keeps incomplete records, mixes personal and business spending, or is unaware that a cost qualifies for deduction. Over time, the cumulative effect of missed deductions can be significant.
Tax implications
- Documentation is the deciding factor. An expense that is genuinely deductible but lacks supporting evidence (invoice, receipt, contract) may still be disallowed if queried.
- Capital versus revenue expenditure is treated differently. Revenue expenses are generally deductible in the year incurred; capital expenditure is typically relieved over time through capital allowances.
- Personal expenses run through the business are a frequent source of disallowance and, in some cases, scrutiny, since they fail the "wholly and exclusively" test.
- Related-party transactions require particular care, as arrangements between connected businesses or individuals may be reviewed more closely.
Step by step: how to review your deductions
- Separate business and personal accounts, so expenses are clearly attributable.
- Collect and retain supporting documents — invoices, receipts, contracts and bank statements — for every claimed expense.
- Classify expenses correctly between revenue (deductible in the year) and capital (relieved through capital allowances).
- Review statutory and professional fees paid during the year to confirm they have been captured.
- Check for bad debts that meet the conditions for write-off and deduction.
- Reconcile your expense ledger against your bank statements to identify any omissions.
- Have your computation reviewed before filing to confirm each deduction is properly supported.
Why engage a professional consulting firm
- Identifying overlooked deductions that a business owner without accounting training may miss.
- Correct classification between revenue and capital expenditure.
- Documentation review, to confirm that claims can withstand scrutiny if queried by the NRS.
- Consistency year-on-year, so deductions are not claimed inconsistently across periods.
Why every business should comply
Claiming only properly supported, genuinely allowable deductions, and paying the resulting tax on time, keeps a business's filings defensible. Overstated claims can lead to disallowance, additional assessments, interest and penalties if reviewed. Accurate claims, on the other hand, ensure a business is not paying more tax than the law requires.
Tips on deductions and documentation
- Keep a dedicated business bank account to simplify expense tracking.
- Request proper invoices, not just informal receipts, from suppliers and service providers.
- Log the business purpose of ambiguous expenses (e.g. entertainment, travel) at the time they are incurred.
- Review capital allowance schedules annually to ensure qualifying assets are properly claimed.
- Retain records for the statutory period required under the Nigeria Tax Act.
Relevant law
- Nigeria Tax Act, 2025 (deductibility principles and capital allowances provisions)
- Nigeria Tax Administration Act, 2025 (record-keeping requirements)
Frequently asked questions
What is the general test for a deductible expense? That it was incurred wholly, exclusively, necessarily and reasonably for business purposes.
Can I deduct rent for business premises? Yes, where the premises are used for business purposes and the rent is properly documented.
Are capital purchases deductible immediately? Generally not. Capital expenditure is typically relieved over time through capital allowances rather than deducted in full in the year of purchase.
What happens if I claim an expense without a receipt? The claim may be disallowed if the NRS reviews the return and finds insufficient supporting evidence.
Can personal expenses be claimed through the business? No. Expenses must relate wholly and exclusively to the business to be deductible.
Where you need further assistance: You may contact US & CO. (Chartered Accountant), a professional tax consulting firm in Lagos, Nigeria. 📞 WhatsApp: 08056219998 📧 Email: info@usc.com.ng 🌐 Website: https://www.usc.com.ng
Footnote: This article is for general information only. It is not complete investment, tax or legal advice. Deductibility depends on the specific facts and current law. Readers should consult a qualified professional before making any investment or tax decision.
