Definition
Operating expenses (OpEx) are the day-to-day costs of running a business that are not directly tied to producing the goods or services sold. They cover salaries, rent, utilities, marketing, software subscriptions, professional fees, and similar overhead. On the income statement, OpEx sits between gross profit and operating profit: operating profit equals gross profit minus operating expenses.
What operating expenses mean in practice
For a bookkeeper, OpEx is the bulk of expense activity in any service business and a large slice in any product business. Salaries are usually the single biggest line; rent, software, and professional fees come next. The OpEx total in a given period gives the most direct measure of fixed overhead.
The most useful OpEx analysis is period-over-period trend. A monthly comparison against the same month last year flags every recurring cost that has changed: a salary increase, a software vendor that pushed through a price rise, a rent step-up, a new advertising programme. Outliers (one-off recruitment fees, legal advice on a specific matter, conference attendance) are usually obvious. The discipline of looking at OpEx monthly catches cost creep before it becomes structural.
A practical example: a UK consultancy’s October-December 2026 quarter. Salaries 35,000. Rent 4,500. Software subscriptions 3,200. Professional fees 1,800. Marketing 2,100. Insurance 850. Office supplies 350. Travel 1,200. Training 800. Telephone and internet 300. Bank fees 100. Total OpEx for the quarter: 50,200. Gross profit for the quarter was 72,000, so operating profit is 21,800 (about 30% operating margin on quarterly revenue of 95,000).
How operating expenses work by country
United Kingdom
Most OpEx is deductible for corporation tax under CTA 2009 section 54: an expense is deductible if “wholly and exclusively” laid out for the purposes of the trade. Notable disallowed categories: client entertainment (UK and overseas), civil and criminal fines, depreciation per the books (replaced by capital allowances), and certain provisions until they are actually paid out. Staff entertainment is allowable up to 150 per head per year provided every employee is invited.
Australia
Most OpEx is deductible under section 8-1 of the Income Tax Assessment Act 1997 if “incurred in producing assessable income”. The list of disallowed categories: entertainment (largely non-deductible under section 32-5), fines and penalties (specifically disallowed under section 26-5), depreciation per the books (replaced by Division 40 tax depreciation), and GST input tax credits not yet claimed.
Canada
Most OpEx is deductible under section 18 of the Income Tax Act if incurred for the purpose of earning income. The CRA’s standard disallowed categories: 50% of meals and entertainment, fines and penalties (section 67.6), club dues, depreciation per the books (replaced by capital cost allowance). Section 67 also limits “unreasonable” amounts paid to non-arm’s-length parties (often relevant when a closely-held company pays a high salary to an owner-employee’s family member).
New Zealand
Most OpEx is deductible under section DA 1 of the Income Tax Act 2007 if “incurred in deriving assessable income”. Entertainment is 50% deductible (subject to specific exceptions for marketing-related entertainment); fines and bribes are non-deductible; depreciation per the books is replaced by IRD-prescribed rates from the Depreciation Rates schedule.
Singapore
Most OpEx is deductible under section 14 of the Income Tax Act if “incurred wholly and exclusively in the production of income”. Motor expenses on private cars (any car not registered as a commercial vehicle) are disallowed under section 15(1)(k). Entertainment of a non-business nature is disallowed. Depreciation per the books is replaced by capital allowances under sections 19, 19A, and 19A(2).
Related terms
Operating expenses sit between gross profit and operating profit on the income statement:
- Gross profit is the sub-total above OpEx.
- Net profit is the bottom line after OpEx, interest, and tax.
- COGS is the direct cost above gross profit (distinct from OpEx).
- Profit margin is the ratio metric that depends on OpEx.
- The income statement is the statement that displays OpEx.
- Capital expenditure is the opposite categorisation: balance-sheet rather than income-statement.
See also
For the OpEx vs CapEx distinction in more depth, see the capital expenditure entry.
FAQ
See the answered questions above for OpEx vs CapEx, typical SMB OpEx categories, and tax-deductibility rules.