Consulting is one of the most common forms of self-employment in the UK. Whether you are a management consultant, IT consultant, HR consultant or specialist adviser, the core accounting principles are the same: keep accurate records, understand your tax obligations and structure your affairs efficiently.
The high-value, low-overhead nature of consulting means your tax planning decisions have an outsized impact on your take-home pay.
Business structure
The right structure depends on your income level, IR35 exposure and personal preferences.
| Structure | Best for | Tax treatment |
|---|---|---|
| Sole trader | Starting out, lower earnings | Income Tax + NIC on profits via Self Assessment |
| Limited company | Higher earnings, outside IR35 | Corporation Tax, then salary + dividends |
| LLP | Multiple partners | Each partner taxed individually |
Most consultants earning over £40,000-£50,000 benefit from operating through a limited company. The salary-dividend split saves significant tax compared to sole trader rates.
The numbers
For a consultant earning £100,000 gross profit (after expenses):
| Method | Approximate take-home |
|---|---|
| Sole trader (all Income Tax + NIC) | £67,000-£70,000 |
| Limited company (optimal salary + dividends) | £76,000-£80,000 |
The exact figures depend on your personal circumstances, but the limited company advantage of £8,000-£12,000 per year is typical at this income level.
IR35 for consultants
If you work through a limited company and provide your services to a single client for an extended period, IR35 is a consideration. The rules are the same as for contractors – if HMRC determines that you would be an employee if engaged directly, your income is taxed as employment income.
Factors that help demonstrate outside IR35
- You have multiple clients (or genuinely seek them)
- You can send a substitute to do the work
- You have no mutuality of obligation between engagements
- You control how you work – you provide expertise, not supervised labour
- You bear financial risk – fixed-fee projects, own equipment, professional indemnity insurance
- You have a business presence – website, marketing, business development activity
Consultants who work on defined projects with clear deliverables are generally in a stronger position than those who provide ongoing resource augmentation.
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Invoicing
Consulting invoices should clearly show:
- Your business name and address
- Client name and address
- Invoice number and date
- Description of services (project name, period, deliverables)
- Rate (daily, hourly or fixed fee) and quantity
- Net amount
- VAT (if registered) – rate and amount
- Total amount due
- Payment terms
- Your bank details
For guidance on invoice requirements, see our guide on what is an invoice.
Payment terms
Standard payment terms for consulting work are 14 to 30 days. Longer terms are common with larger corporates (45-60 days). Include your terms on every invoice and follow up promptly when payments are late.
Allowable expenses
Consulting businesses typically have low overheads, which makes claiming every legitimate expense even more important:
Home office
If you work from home (as most consultants do at least partly), claim your home office costs:
- Flat rate – £10-£26 per month depending on hours worked from home
- Actual proportion – percentage of rent/mortgage interest, council tax, utilities, broadband based on the room(s) used
Travel
- Travel to client sites (if they are temporary workplaces)
- Hotels for overnight stays on client business
- Subsistence – meals while travelling for business
- Flights for international or distant client meetings
Remember the 24-month rule – if you work at the same client site for more than 24 months, it becomes a permanent workplace and travel costs are no longer deductible.
Professional development
- Conferences and industry events
- Books and publications related to your field
- CPD courses and certifications
- Professional body memberships (CMI, ICF, MCA, sector-specific bodies)
Technology and tools
- Laptop, monitor, peripherals
- Software subscriptions – project management, communication, design tools
- Cloud storage and hosting
- Mobile phone (business proportion)
Insurance and professional services
- Professional indemnity insurance – essential for consultants
- Accountancy fees
- Legal fees for contract review
- Business banking fees
VAT
The VAT threshold is £90,000. Many consultants exceed this.
Business-to-business clients
If your clients are all VAT-registered businesses, registering for VAT has no real commercial impact – they reclaim the VAT you charge. You benefit by being able to reclaim input VAT on your expenses.
International clients
For services supplied to business clients outside the UK, the general rule is that the supply is outside the scope of UK VAT (the place of supply is where the customer belongs). You do not charge VAT but must still report the sale on your VAT return in the appropriate box.
For EU clients, the reverse charge applies – the client accounts for VAT in their country.
Flat Rate Scheme
The Flat Rate Scheme can simplify VAT. For management consultants, the flat rate is typically 14% of gross turnover. If your expenses are low (as they usually are for consultants), this means you keep the difference between the 20% you charge and the 14% you pay. However, if you are classified as a “limited cost trader” (goods purchases less than 2% of turnover), the rate is 16.5%, making the scheme less beneficial.
Tax planning strategies
Pension contributions
Employer pension contributions from your limited company are deductible for Corporation Tax and free of Income Tax and NIC for you. Within the annual allowance, this is one of the most effective ways to build wealth tax-efficiently.
Timing income and expenses
If you have control over when you invoice (common in consulting), you can manage your taxable income across accounting periods:
- Delay invoicing a December project until January if it moves income into a lower-tax period
- Bring forward expenses – prepay annual subscriptions before year end
Salary sacrifice
If you are the director of your own company, you can sacrifice salary in exchange for employer pension contributions, saving both employee and employer NIC.
Capital allowances
Claim the Annual Investment Allowance on equipment purchases – laptops, monitors, office furniture.
Record-keeping
Consultants should keep:
- All invoices issued and received
- Contracts and engagement letters with clients
- Expense receipts and records
- Bank statements
- Mileage logs for business travel
- Time records if billing by the hour or day
Use accounting software to automate bank feeds, invoicing and VAT calculations. For a consulting business with relatively few transactions, the time investment is minimal and the return is significant.
Common consultant accounting mistakes
- Not separating personal and business finances – essential for limited company directors
- Over-claiming expenses – only genuinely business expenses qualify
- Ignoring IR35 – get a professional review if there is any doubt
- Not saving for tax – set aside 25-30% of gross income in a separate account
- Missing the VAT threshold – monitor your rolling 12-month turnover
- Not claiming pension contributions – the most tax-efficient extraction method for many consultants
- Paying too much salary – the optimal salary is usually at or below the NIC threshold
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