Can My Accountant File My Self Assessment and Company Tax Return Together?

Introduction

If you run a limited company and pay yourself through salary or dividends, you will need to deal with two separate tax returns each year — your personal Self Assessment tax return and your company’s Corporation Tax return. It can seem confusing to manage both, and many business owners wonder whether their accountant can file them together as one combined process.

The short answer is that while both can be prepared by the same accountant, they are legally separate filings that must be submitted individually to different parts of HMRC. However, your accountant can coordinate both returns so that they align perfectly, ensuring your income and company profits are reported correctly.

This article explains how the two tax returns differ, how your accountant handles them, what information links them together, and how managing them jointly through one accountant benefits your business.

Understanding the Two Types of Tax Returns

Your Company Tax Return is a corporate filing submitted by your limited company to HMRC after the end of its financial year. It reports your company’s income, expenses, and profits, and calculates how much Corporation Tax is due. The company files this return using form CT600, along with a full set of statutory accounts prepared under UK accounting standards.

Your Self Assessment Tax Return is a personal filing that reports your individual income for the tax year running from 6 April to 5 April. If you are a company director, it usually includes your salary, dividends from the company, and any other income such as property, investments, or self-employment.

Although these two filings are separate, they are closely linked because the figures from the company return often feed directly into your personal return. For example, the company accounts show how much you were paid in salary and dividends, which your accountant must then include in your personal tax return.

Can They Be Filed Together?

In terms of process, the company tax return and Self Assessment are filed separately to HMRC using different systems. The company return is filed through HMRC’s Corporation Tax gateway, while the Self Assessment is submitted through the individual tax system.

However, your accountant can prepare and submit both at the same time, coordinating them so that the deadlines, figures, and supporting records all match. This approach gives you one seamless service even though two formal submissions take place.

For example, your accountant might complete your company accounts for the year ended 31 March 2025 and then immediately prepare your personal Self Assessment for the 2024 25 tax year using the dividend and salary figures from those same accounts. Both returns will align perfectly, avoiding errors or mismatched information.

How Your Accountant Manages Both Returns

A professional accountant can handle the entire process efficiently. Here is how they typically manage both returns together:

1. Prepare company accounts and CT600
   The accountant starts by finalising your company’s bookkeeping, preparing year-end accounts, and calculating the Corporation Tax liability.

2. Extract personal income details
   Once the accounts are complete, they identify the exact amounts of director’s salary, dividends, and any reimbursed expenses.

3. Use those figures in your Self Assessment
   These amounts are then included in your personal tax return, along with any other income you earn outside the company.

4. Coordinate submission and payment deadlines
   While the deadlines differ, your accountant can ensure both are filed ahead of time and that you understand what needs to be paid and when.

This joined-up approach keeps your personal and business tax affairs consistent and prevents common mistakes such as double-counting income or missing allowable deductions.

Deadlines for Each Return

The deadlines for the two returns are different, which is one reason they cannot be filed as a single submission:

• Company Tax Return (CT600): Due 12 months after the end of the company’s accounting period, but Corporation Tax must be paid within nine months and one day.

• Self Assessment Tax Return: Due by 31 January following the end of the tax year, with payment due on the same date.

For example, if your company’s financial year ends on 31 March 2025, your CT600 must be filed by 31 March 2026, and Corporation Tax paid by 1 January 2026. Your personal Self Assessment for the 2024 25 tax year would be due by 31 January 2026.

An accountant can align the preparation work so that both are completed together, saving time and ensuring you have full visibility of all tax liabilities.

Advantages of Having the Same Accountant Handle Both

Using one accountant for both your company and personal returns provides clear benefits:

• Consistency: The same person prepares both sets of figures, ensuring dividends, salary, and tax payments match exactly.

• Efficiency: Shared records and bookkeeping make the process faster and reduce administrative work.

• Accuracy: Avoids duplication or omission of income between company and personal filings.

• Tax planning opportunities: Your accountant can advise on the most efficient mix of salary and dividends to minimise overall tax.

• Simplified communication: You deal with one point of contact for all your financial and tax matters.

This joined approach gives you a complete picture of your company’s performance and your personal tax position at the same time.

What You Still Need to Provide

Even though your accountant manages both returns, you will still need to supply:

• Personal income details outside the company (such as property, interest, or freelance work)

• Details of any personal pension contributions

• Information on benefits in kind or expenses paid personally

• Confirmation of dividend payments, even if they came from multiple companies

Providing full and accurate information allows your accountant to complete both returns correctly and ensure you pay the right amount of tax.

Common Misunderstandings

Some company directors believe that because they pay an accountant for “end of year accounts,” it automatically includes their personal Self Assessment. In reality, most accountants treat these as separate services unless clearly stated in your engagement letter. Always confirm whether your annual package includes both filings to avoid last-minute surprises.

Another misconception is that both returns are due at the same time or filed as one. While your accountant can complete them together, HMRC’s systems do not merge the submissions. Each is processed separately even if the figures link.

Tax Planning Benefits of Combined Management

Having one accountant oversee both returns allows for smarter tax planning. For instance, they can decide the most tax-efficient balance between salary and dividends, time your income around year-end, and ensure both personal and company allowances are fully used.

They can also forecast your Corporation Tax and personal tax liabilities together, so you know exactly what you need to pay and when. This helps avoid cash flow shocks and reduces the risk of penalties.

What Happens If You Use Different Accountants

It is possible to have one accountant handle the company return and another manage your Self Assessment, but it is rarely ideal. The two professionals must share information accurately, and any communication gap can lead to mismatched figures or missing data.

For example, if one accountant records a £10,000 dividend payment in the company return but the other forgets to include it in your Self Assessment, HMRC could flag an inconsistency. Using the same accountant avoids this issue entirely.

Conclusion

Your accountant cannot technically file your Self Assessment and company tax return as one single submission, because HMRC treats them as separate obligations. However, your accountant can prepare and submit both together in a coordinated way, ensuring the figures align and deadlines are met.

This joined approach provides accuracy, efficiency, and valuable tax planning opportunities. It ensures your company profits, salary, and dividends all link seamlessly, giving you a complete financial picture.

If you are unsure whether your current accounting package includes both filings, ask your accountant to confirm. Managing both under one roof is often the simplest and most reliable approach for any company director.