Corporation Tax Explained for UK Limited Companies

Corporation Tax applies to the taxable profits of UK limited companies and some other organisations. For many company directors, the tax feels straightforward: prepare accounts, file a CT600 and pay HMRC.

Real company tax rarely stays that neat.

A limited company has its own tax position. The director has a separate personal tax position. The accounts, tax computation, payroll records, dividends, director loan account and VAT returns should all tell the same story.

For company directors in London, this matters because businesses often grow quickly, take on staff, buy assets, hold cash, work internationally or move between contractor and trading company structures.

Tax Accountant London provides Corporation Tax return preparation and company tax advice where the CT600, accounts and director position need proper review.

What Corporation Tax covers

Corporation Tax is charged on company profits. These profits may come from trading income, investment income, property income, chargeable gains or other taxable receipts.

A company reports its position to HMRC through a Company Tax Return, often called a CT600. The return includes the tax computation, accounts and supporting information.

GOV.UK explains the Company Tax Return rules on its Company Tax Returns page. That guidance confirms that a company may still need to file even where it has made a loss or has no Corporation Tax to pay.

The tax return should not be treated as a simple upload. It should reflect the company’s real commercial and tax position.

Corporation Tax is not the same as company accounts

Company accounts and the Corporation Tax computation are connected, but they are not identical.

Accounts show the company’s financial performance under accounting rules. The tax computation adjusts those figures for tax rules.

Some expenses shown in the accounts may not receive tax relief. Some capital purchases may need capital allowance treatment. Some income may need tax adjustments. Timing differences can also arise.

For example, entertaining may appear in the accounts, but it may not reduce taxable profit. Depreciation may appear in the accounts, but the tax computation usually uses capital allowances instead.

A correct CT600 needs both accounting knowledge and tax judgement.

Corporation Tax rates and profit levels

Corporation Tax rates can depend on the level of company profits. GOV.UK explains current Corporation Tax rates, including the small profits rate, main rate and marginal relief rules.

At the time of writing, companies with profits up to the small profits limit may pay at the small profits rate. Companies with profits above the upper limit may pay at the main rate. Companies between the limits may qualify for marginal relief.

Associated companies can affect these thresholds. This point matters for directors who control more than one company.

A director may assume each company has a full threshold. That may be wrong if the companies are associated.

Corporation Tax deadlines

Corporation Tax has two main deadlines.

The payment deadline usually comes before the filing deadline. For many companies, Corporation Tax must be paid 9 months and 1 day after the end of the accounting period. The Company Tax Return normally has a 12-month filing deadline.

This order catches some directors out. They wait for the CT600 before thinking about payment. By then, the payment deadline may have passed.

A company should estimate its Corporation Tax before the payment date. Good bookkeeping makes that possible.

Late payment can lead to interest. Late filing can lead to penalties. Repeated failures can damage HMRC confidence in the company.

Allowable company expenses

A company can usually claim expenses incurred wholly and exclusively for the business. Common costs include wages, rent, software, professional fees, insurance, travel, marketing, accountancy, subcontractors and business supplies.

However, not every company payment reduces Corporation Tax.

Personal expenses, client entertaining, some legal costs, fines and poorly evidenced costs may need adjustment. Mixed costs should be reviewed carefully.

For owner-managed companies, the line between business and personal spending often creates issues. A company card used for personal items can create director loan or benefit problems.

A strong company tax file should include invoices, receipts, contracts, payroll records and clear bookkeeping descriptions.

TIP: Review the director loan account before the company year end.
It is easier to fix drawings, dividends and repayments before the accounts are finalised.

Director loan accounts and Corporation Tax

Director loan accounts cause many company tax problems.

A director loan account records money taken from or paid into the company outside salary, dividends or expense reimbursement. If a director takes more from the company than they are entitled to, the account may become overdrawn.

An overdrawn director loan can create company tax charges, benefit issues and personal tax consequences.

The problem often starts with informal withdrawals. A director pays personal costs from the company bank account and plans to “sort it later”. Later, the accounts show a large balance.

Dividends cannot always fix the issue. Dividends need distributable profits and proper records. Backdating paperwork can create further risk.

A company should track director drawings during the year, not only after year end.

Dividends and company profits

Dividends are paid from post-tax company profits. They should not be treated as a casual withdrawal method.

Before declaring dividends, directors should consider whether the company has enough distributable reserves. They should also keep dividend vouchers and meeting records.

If dividends exceed available profits, the payment may be unlawful or treated differently for tax.

For London company directors, this issue often appears where cashflow looks healthy, but tax liabilities, VAT, payroll costs or unpaid suppliers reduce the real reserve position.

The company bank balance does not prove that dividends are available.

Company accounts should support the dividend position.

Capital allowances and business assets

Companies often buy equipment, vehicles, computers, machinery or fixtures. These purchases may not receive tax relief in the same way as ordinary expenses.

Instead, capital allowances may apply.

The timing and type of asset matter. Some assets may qualify for Annual Investment Allowance or other reliefs. Cars often need special attention because emissions and usage can affect tax treatment.

A company planning a large purchase near year end should take advice before committing. The invoice date, asset type, use and payment terms can all affect the tax result.

A rushed decision made only to reduce tax may not help if the asset does not support the business.

Corporation Tax and VAT should connect

A company’s CT600 should make sense when compared with VAT returns, payroll filings and accounts.

If VAT returns show sales of £400,000, but the accounts show much lower turnover, HMRC may ask questions. There may be a good explanation, but the file should support it.

VAT coding errors can also affect profits. Sales recorded incorrectly, input VAT claimed wrongly or reverse charge entries mishandled can distort figures.

Tax Accountant London provides VAT return and VAT compliance support where VAT records need to align with accounts and company tax.

Good tax compliance works across the whole business, not one return at a time.

Corporation Tax for property companies

Property companies have their own issues.

Rental income, finance costs, repairs, capital improvements and property disposals need careful treatment. A company may deduct interest differently from an individual landlord, but that does not mean every cost qualifies automatically.

A property company may also face Corporation Tax on chargeable gains when it sells property. The company position then links to the director’s personal tax position when funds are extracted.

Directors should think about both stages. Tax inside the company is only one part of the overall result.

For property investment companies, bookkeeping should separate each property. That helps identify profit, finance costs and repairs clearly.

Corporation Tax for contractors and consultants

Contractor companies often have smaller accounts, but they can still carry risk.

IR35, director salaries, dividends, travel expenses, home office costs, training and equipment all need proper review.

If a contractor moves inside IR35, income may be taxed differently. If the company receives income that has already suffered employment-style deductions, the accounting and tax treatment needs care.

A contractor should not assume that small company accounts mean simple tax.

Company closure also needs planning. Funds left in the company may be extracted as dividends, salary, repayment of loans or capital distribution depending on the facts.

A practical example

A London consultancy company makes £180,000 profit before director drawings. The director has taken £60,000 during the year, but no payroll has been operated and no dividends have been documented.

The accounts show strong profit, but the director loan account may be overdrawn. The company also bought equipment, paid for travel and used the company card for some personal costs.

A basic CT600 may calculate Corporation Tax. A proper review would ask more.

Can dividends be declared from available profits? Does the director loan need clearing? Are any benefits reportable? Do capital allowances apply? Does the company fall within marginal relief? Are VAT returns consistent with turnover?

That review can prevent tax errors from spreading into later years.

Common Corporation Tax mistakes

Common mistakes include filing late, paying after the deadline, claiming personal costs, ignoring director loans, declaring dividends without reserves, missing capital allowances, treating depreciation as tax relief, and failing to adjust non-deductible expenses.

Other problems arise where associated companies reduce thresholds, property costs are misclassified, or overseas activity creates UK or foreign tax issues.

A company director should not wait until the CT600 is due before reviewing these points.

Year-end planning gives the company more options.

When advice is sensible

Advice is sensible where profits have increased, the company has director loan issues, dividends are unclear, large assets have been bought, property is involved, VAT records are messy, or HMRC has raised questions.

It is also sensible where the company trades overseas, has more than one director, has associated companies or plans to sell assets.

A company tax advisor should look beyond the CT600. The best advice links accounts, tax, cashflow and director income.

That approach gives the company a cleaner tax position and fewer surprises.

Conclusion

Corporation Tax is not just a filing requirement. It reflects how the company has traded, spent money, paid directors, bought assets and kept records.

A strong CT600 should connect with the accounts, VAT returns, payroll records, dividends and director loan account. It should also use reliefs correctly and avoid weak expense claims.

Company directors do not need to know every Corporation Tax rule. However, they should know when a company decision creates a tax consequence.

This article is for general information only. It is not personal tax advice and should not be relied on for your own circumstances. Corporation Tax depends on company profits, accounts, expenses, assets, directors’ drawings, VAT records, associated companies and the accounting period involved.

For tailored support, contact Tax Accountant London for personalised Corporation Tax advice, CT600 preparation, company tax review or guidance based on your own circumstances.