Those responsible for the accounts and tax compliance of private limited companies must ensure they are fully aware of the relevant obligations and statutory deadlines.

Following the end of each financial year, a private limited company is required to prepare full annual accounts and submit a Company Tax Return. The deadline for filing the first set of accounts must be filed with Companies House within 21 months of the date of incorporation. Thereafter, annual accounts must be filed within 9 months of the end of each financial year.

Corporation Tax is payable 9 months and 1 day after the end of the relevant accounting period. As a result, the tax liability will typically fall due before the filing deadline for the Company Tax Return.

In most cases, the Company Tax Return must be submitted within 12 months of the end of the accounting period. Filing is required to be completed online in iXBRL format, using either HMRC’s own software or approved third-party software.

The Corporation Tax accounting period will generally correspond with the 12-month company financial year covered by the annual accounts.

Penalties may be imposed by both Companies House and HMRC for late filing or non-compliance, and it is therefore essential that all deadlines are carefully monitored and adhered to.

The rate of Corporation Tax payable depends on the level of a company’s taxable profits. The main rate is 25% and applies where profits exceed £250,000. At the other end of the scale, companies with profits of £50,000 or less benefit from the Small Profits Rate, which remains at 19%.

For businesses with profits between these thresholds, marginal relief applies. Rather than facing a sharp increase in tax, companies experience a gradual rise in the effective rate as profits move from £50,000 towards £250,000. This ensures a smoother transition between the lower and higher rates.

It is important to note that the £50,000 and £250,000 thresholds are not always fixed. They are reduced where a company has associated companies or where the accounting period is shorter than 12 months, which can bring more businesses into the marginal relief band.

In practice, Corporation Tax is initially calculated at the main rate of 25%, with marginal relief then deducted to arrive at the final liability. The relief is calculated using a standard fraction of 3/200.

The marginal rates help smaller companies to pay less Corporation Tax based on their profit level and circumstances. 

After the end of its financial year, a private limited company must prepare full annual accounts and submit a company tax return. In most cases, the tax return must be filed within 12 months of the end of the accounting period it covers, and filing must be completed online.

There are penalties for the late submission of company tax returns. The filing penalties will increase for company tax returns where the filing date falls on or after 1 April 2026.

The penalties are designed to encourage companies to file their Corporation Tax returns by the required deadline. Fixed penalties for late filing were originally set in 1998 and have remained unchanged since then. Over time, inflation has significantly reduced the real value of these penalties and therefore their deterrent effect. In real terms, the penalties are now worth roughly half of what they were when first introduced.

The increase in company late filing penalties will see the doubling of fixed penalties. From 1 Apri 2026, a return that is filed late will attract a penalty of £200 instead of the current £100. If the return is more than three months late, the penalty will increase to £400, compared with the current £200. Higher penalties will continue to apply where a company repeatedly files late returns. Where there are three successive failures to file on time, the penalty will increase from £500 to £1,000, and where the return is more than three months late after three consecutive failures, the penalty will rise from £1,000 to £2,000.

Ensuring that company tax returns are submitted on time will help companies avoid unnecessary penalties and additional compliance costs.

If your company profits sit between £50,000 and £250,000, marginal relief can soften the jump from 19% to 25% Corporation Tax.

The Corporation Tax main rate applies to companies with taxable profits above £250,000 and is currently set at 25%. Companies with profits of up to £50,000 are subject to the Small Profits Rate, which remains at 19%.

For companies with profits falling between £50,000 and £250,000, marginal relief applies. This creates a gradual increase in the effective rate of Corporation Tax between the small profits and main rates, rather than a sudden jump. The lower and upper profit limits are proportionately reduced where an accounting period is shorter than 12 months or where a company has associated companies.

The effect of marginal relief is that the effective Corporation Tax rate increases steadily from 19% once profits exceed £50,000, reaching the full 25% rate when profits exceed £250,000.

In practice, Corporation Tax is calculated by applying the main rate of 25% to total taxable profits and then deducting the marginal relief due. The marginal relief standard fraction is 3/200. HMRC provides an online marginal relief calculator to help companies determine the correct amount of Corporation Tax payable based on their profit level and circumstances.

If your business works in film, TV, games or the arts, Creative Industry Tax Reliefs could reduce your Corporation Tax bill and may even generate a payable tax credit.

Creative Industry Tax Reliefs (CITR) are a range of UK Corporation Tax reliefs designed to support companies operating in the creative sector. The reliefs allow qualifying companies to increase the amount of allowable expenditure when calculating their taxable profits, thereby reducing the Corporation Tax they are required to pay. Where a company is loss-making, it may be possible to surrender those losses in exchange for a payable tax credit.

CITR covers a wide variety of creative activities. Reliefs are available for film, animation, high-end television, children’s television and video game production, as well as for theatre, orchestra performances, and museums and galleries exhibitions. More recently, the Audio-Visual Expenditure Credit and the Video Games Expenditure Credit have been introduced, offering an alternative credit-based system for eligible productions.

To qualify for CITR, films, television programmes and video games must meet specific cultural criteria. This is usually achieved by passing a formal ‘cultural test’, which assesses various factors such as content, setting and the nationality of key personnel. Alternatively, a production may qualify through an internationally agreed co-production treaty. Meeting these requirements allows the production to be certified as a British film, British programme or British video game.

Certification is administered by the British Film Institute (BFI) on behalf of the Department for Culture, Media and Sport. The BFI can issue an interim certificate while production is ongoing, followed by a final certificate once the project has been completed. This certification is a key requirement for claiming the relevant tax reliefs.