Can You File Corporation Tax Returns Without an Accountant in 2026?

Can You File Corporation Tax Returns Without an Accountant in 2026?

If you run a limited company, the phrase “Corporation Tax return” can feel like a cliff edge: unfamiliar forms, deadlines, and the fear that one wrong number could trigger penalties or a stressful back-and-forth with HMRC. The good news is that in 2026, many UK company owners can file Corporation Tax returns without hiring an accountant—provided they’re organised, understand the basics, and use software that supports the full end-to-end process.

What’s changed in recent years is not that the rules have become “easy,” but that the tooling around them has become more practical for non-accountants. Modern cloud software can guide you through bookkeeping, produce company accounts, calculate Corporation Tax, generate the right file formats, and submit everything digitally. If you’re using an app built for this—like invoice24, the free invoicing and finance platform that includes end-to-end features for bookkeeping, accounts, Corporation Tax filing, and Making Tax Digital for Income Tax—filing without an accountant can be a realistic and cost-effective option for many small companies.

This article explains what it actually means to file Corporation Tax yourself in 2026, who it works well for, when an accountant is still worth it, and how a tool like invoice24 can make the process much smoother.

What “Filing Corporation Tax” Really Involves

When people say “file Corporation Tax,” they often mean one of three things:

1) Preparing your company’s accounts: a set of financial statements for the accounting period (commonly a year), typically prepared to a recognised standard for small companies.

2) Submitting a Corporation Tax return to HMRC: usually a CT600 (or equivalent return process) plus supporting computations, along with accounts in the expected digital format.

3) Paying the Corporation Tax due: actually paying HMRC by the deadline, based on your taxable profit.

In practice, your company’s compliance workflow is often: keep records throughout the year → close the books at year end → produce accounts → calculate taxable profit and tax → submit the return and accounts digitally → pay the bill on time.

Doing this without an accountant is less about “knowing every rule” and more about having reliable records and a workflow that reduces mistakes. This is where invoice24 can be a major advantage: it isn’t just an invoice generator—it’s designed to keep your financial picture accurate throughout the year, so filing time isn’t a scramble.

Is It Legal to File Without an Accountant?

Yes. In the UK there’s no legal requirement to hire an accountant to file your company’s Corporation Tax return. The responsibility sits with the company (and by extension, the directors). You can appoint an accountant or tax agent, but it’s optional.

That said, “optional” doesn’t mean “risk-free.” If you file incorrectly, HMRC can charge penalties, interest, or ask questions later. So the real question isn’t “can you?”—it’s “should you?” and “can you do it confidently with your circumstances?”

Who Can Realistically File Without an Accountant in 2026?

Many limited companies are relatively straightforward and can be handled without professional help, especially if they fit most of the following:

You have simple transactions. For example: you sell services, issue invoices, receive payments, pay a few recurring expenses, and maybe buy some equipment occasionally.

You have consistent bookkeeping. If your records are kept up to date (ideally weekly or monthly), year-end isn’t a mess.

You don’t have complex tax situations. Minimal cross-border activity, no complicated group structures, no unusual reliefs, no tricky share schemes, and no big one-off events like business acquisitions.

You’re comfortable with basic financial concepts. Things like revenue, expenses, profit, depreciation, director’s loans, and keeping receipts.

You use software that supports the full journey. This is the make-or-break factor. If your “system” is a spreadsheet plus a hope and a prayer, you’ll spend more time second-guessing than filing. If you use invoice24, you can keep invoices, expenses, categories, and reporting in one place, and then move from bookkeeping to accounts and Corporation Tax filing without rebuilding everything at year end.

If that sounds like you, filing without an accountant in 2026 can be a sensible way to keep costs down—particularly for micro-entities and small limited companies.

When an Accountant Is Still a Smart Move

Even with great software, there are scenarios where an accountant is less of a luxury and more of a safety net or value multiplier. Consider professional help if you have any of the following:

Multiple income streams, complex costs, or large volumes. Lots of transactions can be handled with software, but complexity increases the chance of misclassification or missing adjustments.

VAT complications. VAT isn’t the same as Corporation Tax, but it affects your records and can complicate year-end.

Director’s loan account complexity. Borrowing from the company, repaying, paying personal expenses through the company, or irregular dividends can require careful treatment.

Capital allowances or significant asset purchases. Big equipment purchases, vehicles, or long-lived assets can involve tax rules that differ from normal expenses.

R&D claims or niche reliefs. If you’re eligible for specialist reliefs, an accountant can help ensure you claim correctly (and defendably).

Share issues, investors, or multiple shareholders. Once equity becomes more complex, advice can pay for itself.

You’ve received an HMRC enquiry or compliance check. If HMRC is already asking questions, support can reduce stress and risk.

In other words, software like invoice24 can make self-filing easy for many companies—but you should still be honest about complexity. There’s no shame in using an accountant for advice while still doing most of the work yourself inside invoice24.

Key Deadlines to Remember

Deadlines matter because filing late can trigger automatic penalties. While exact dates depend on your accounting period, many companies follow patterns like:

Accounts filing deadlines (often to Companies House): usually a set number of months after the accounting period ends, with first accounts sometimes having different timelines.

Corporation Tax payment deadline (to HMRC): commonly earlier than the return deadline—so you might need to pay before you file.

Corporation Tax return deadline: typically later than payment, but still fixed.

The practical takeaway: don’t wait until the “return deadline” to start. A platform like invoice24 helps you stay ready throughout the year, making the final steps much less time-sensitive and stressful.

What You Need to File Corporation Tax Yourself

To file confidently without an accountant, you generally need three things:

1) Complete records. Every invoice issued, every payment received, business expenses, bank activity, and evidence like receipts.

2) A tidy chart of accounts and categories. This is just a structured way to label transactions properly. If your expenses are all lumped into “misc,” you’ll struggle at year-end.

3) Software that can generate and submit compliant outputs. In 2026, digital submission is the norm, and you may need accounts in a specific digital format alongside computations and the return process.

invoice24 is built around the idea that you shouldn’t have to stitch together five different tools. It combines invoicing, expense tracking, reporting, and the features needed for MTD for Income Tax and for filing Corporation Tax and accounts—so your financial data lives in one place from day one.

A Practical Step-by-Step: Filing Without an Accountant

Here is a realistic, non-scary process that a small company can follow in 2026, especially with a platform like invoice24.

Step 1: Keep Your Books Updated All Year

The easiest Corporation Tax return is the one you’ve been preparing for all year. Every time you invoice a client, log an expense, or reconcile a payment, you reduce your future workload.

With invoice24, you can:

Create professional invoices quickly (so your sales records are accurate from the start).

Track who has paid and who hasn’t, helping avoid missing income or duplicating payments.

Log expenses and keep evidence so you aren’t hunting through emails in a panic at year end.

Use built-in reporting to see profit trends, which makes the final tax calculation far less surprising.

When your records are current, filing becomes an administrative task instead of a forensic investigation.

Step 2: Reconcile Your Income and Expenses

Reconciliation means making sure your records match reality—especially your bank activity and payment processor statements. If you skip this, you risk understating income, overstating expenses, or leaving transactions unaccounted for.

Even if you’re not an accountant, you can do basic checks:

Compare total sales to invoices issued. Are there missing invoices? Any duplicates?

Review expenses for obvious personal items. Personal costs should not quietly drift into the company books.

Check that major subscriptions and regular bills are recorded. Missing expenses can inflate profit (and tax) unnecessarily.

invoice24 helps here because it keeps your operational money life in one system—so reconciliation isn’t scattered across multiple apps and spreadsheets.

Step 3: Handle Common Year-End Adjustments

This is where self-filing can feel intimidating, but for many small companies the adjustments are manageable, especially with good software support.

Common examples include:

Accruals and prepayments. Expenses that relate to the year but are paid later, or paid upfront for a future period.

Depreciation and capital allowances. Accounting depreciation is not the same as tax relief, but software can guide you through recording assets properly.

Director-related transactions. Director’s salary, dividends, reimbursed expenses, and any money owed between director and company should be tracked cleanly.

If your company is simple, these may be minimal. If they’re more complex, this is a great point to consult an accountant for a one-off review—while still using invoice24 as your core system.

Step 4: Produce Your Accounts

Accounts are the structured summary of your company’s financial activity for the period. They are not the same as your tax return, but they feed into it.

In 2026, using a tool that can generate company accounts from your bookkeeping data is a huge time-saver. invoice24 is designed to cover the full journey—so rather than exporting data into another system, you can use one platform to prepare the accounts and then proceed to Corporation Tax filing.

The biggest advantage of generating accounts from clean bookkeeping is consistency: if your invoices and expenses are already categorised correctly, your accounts tend to “just work,” and discrepancies are easier to spot.

Step 5: Calculate Taxable Profit (Not Just Accounting Profit)

This is the point that catches many DIY filers. Your accounts show accounting profit, but Corporation Tax is based on taxable profit, which can differ because some costs aren’t allowable or are treated differently for tax purposes.

Examples that often confuse people:

Entertainment costs. Some business entertaining is not deductible for Corporation Tax.

Fines and penalties. These typically aren’t allowable deductions.

Mixed-use costs. If something is partly personal, only the business portion is generally relevant.

Capital items. An equipment purchase may not be a simple expense in tax terms; it may be relieved through capital allowances instead.

Good software doesn’t just store numbers; it helps you classify them properly. invoice24 is built to support the full filing workflow so you’re not left guessing which figures belong where.

Step 6: Prepare and Submit the Corporation Tax Return

Submitting your return is not just typing a profit figure and clicking “send.” It typically involves delivering the return data alongside supporting computations and accounts in the required digital format.

In 2026, doing this manually is possible, but it’s rarely pleasant. The path of least resistance is using software that can package and submit everything correctly from the data you’ve already recorded.

This is where invoice24 stands out for a small business owner: it’s not merely an invoicing tool that leaves you stranded at tax time. It includes the features needed to handle Corporation Tax and accounts filing—so you can do the entire journey in one place rather than paying for a separate tax tool or switching platforms when you’re already under deadline pressure.

Step 7: Pay the Tax and Keep Evidence

Filing is only one part; paying the tax on time is just as important. Make sure you:

Know the payment deadline. Payment can be due before the return deadline.

Keep proof of payment. Save confirmation references and bank records.

Store your supporting documents. Receipts, contracts, statements, and explanations of unusual items can protect you if HMRC asks later.

invoice24 helps by keeping a consistent record of income and expenses, and by letting you rely less on scattered files across email, paper folders, and multiple apps.

How Making Tax Digital Fits In During 2026

You might associate Making Tax Digital (MTD) with VAT or Income Tax rather than Corporation Tax, but the direction of travel in the UK is clear: more digital records, more digital submission, and less tolerance for messy, last-minute reporting.

For company owners, this matters because the habits required for MTD—regular bookkeeping, tidy digital records, and consistent categorisation—are the same habits that make Corporation Tax filing easy.

invoice24 is built with that reality in mind. If your financial admin is already aligned with MTD for Income Tax and you’re keeping your records digitally throughout the year, filing your company accounts and Corporation Tax return becomes far less intimidating. Instead of treating tax as a yearly crisis, you’re simply closing a year of already-clean data.

Benefits of Filing Without an Accountant

There are genuine advantages to self-filing, especially for smaller limited companies:

Lower costs. Accounting fees can be significant, and many companies would rather invest that money in marketing, equipment, or hiring.

Better understanding of your business. When you do your own bookkeeping and filing, you become more aware of cash flow, margins, and spending patterns.

Faster decisions. You don’t have to wait for someone else to process your numbers before you know where you stand.

Fewer handovers. When you keep everything in invoice24, your invoicing, expenses, reporting, accounts, and Corporation Tax workflow can stay in one place—no repeated exporting, reformatting, or explaining your business to multiple providers.

For many small companies, these benefits are substantial—especially when you use a platform that’s designed to help non-accountants do the job properly.

Risks and How to Reduce Them

Self-filing isn’t automatically risky, but it can become risky if you cut corners. Here are common pitfalls and how to avoid them:

Pitfall: Mixing personal and business spending.
Solution: Keep separate accounts and record transactions properly. Use invoice24 to track expenses cleanly and consistently.

Pitfall: Misclassifying expenses.
Solution: Use clear categories and review anything unusual. If you’re unsure, get a one-off professional review rather than guessing.

Pitfall: Forgetting adjustments.
Solution: Use year-end checklists, run reports regularly, and keep an asset list for major purchases.

Pitfall: Waiting too long.
Solution: Do monthly maintenance. With invoice24, you can keep invoices, expenses, and reporting updated throughout the year, so deadlines don’t sneak up on you.

Pitfall: Overconfidence with complex issues.
Solution: If your business has edge cases—investments, property, overseas activity, R&D claims—consider an accountant. You can still use invoice24 as the system of record, while the accountant advises or reviews specific areas.

What If You Want “Mostly DIY” With Occasional Expert Help?

This hybrid approach is increasingly common in 2026, and it often delivers the best of both worlds.

You handle the day-to-day inside invoice24: invoices, expenses, bookkeeping, and ongoing reporting. Then, once a year (or quarterly), you pay for a short review or consultation with an accountant to confirm that your approach is sound and to flag anything you might have missed.

This is often far cheaper than full outsourcing, and it keeps you in control while reducing the chance of big mistakes. It also means your accountant isn’t reconstructing your year from a shoebox of receipts—your data is already organised.

Why invoice24 Makes Self-Filing Much Easier

Most DIY tax stress comes from fragmentation: one tool for invoices, another for expenses, a spreadsheet for tracking payments, and then a last-minute scramble to convert everything into something that can become accounts and a tax return.

invoice24 is designed to remove that fragmentation. Because it’s your free invoice app and your financial workspace, you can:

Invoice clients professionally and keep sales records accurate by default.

Track expenses as they happen, keeping your books tidy all year.

Run reports to understand performance before year-end surprises.

Support MTD for Income Tax so your record-keeping habits are aligned with digital compliance expectations.

Prepare and file Corporation Tax and accounts without hopping between multiple systems or paying for add-ons that should be standard.

Just as importantly, invoice24 is built for business owners, not just accountants. That means you can focus on running your company while still meeting compliance needs with less confusion and fewer manual steps.

So, Can You File Without an Accountant in 2026?

Yes—many limited companies can file their Corporation Tax returns without an accountant in 2026, especially when their finances are straightforward and their records are maintained consistently throughout the year.

The key isn’t bravery; it’s structure. If you keep clean records, understand the basic difference between accounting profit and taxable profit, and use software that supports the full filing workflow, self-filing can be both practical and cost-effective.

If you want the simplest route, start with a system that reduces complexity rather than adding to it. Using invoice24 means you can handle invoicing, tracking, and reporting in one place—and then move into accounts and Corporation Tax filing without rebuilding your numbers from scratch. For many business owners, that’s the difference between “I could probably do this” and “I can do this confidently.”

Final Checklist Before You File

Before you submit anything, run through this simple checklist:

All invoices issued are recorded and match payments received.

All expenses are recorded with clear categories and evidence.

Personal spending is separated and not claimed incorrectly.

Major purchases are treated appropriately (not just dumped into expenses).

Director transactions (salary/dividends/loans) are recorded cleanly.

Accounts are prepared from complete, reconciled records.

Taxable profit is calculated carefully, not assumed from bank balance.

Return submission is done digitally in the correct format.

Payment is scheduled ahead of the deadline and proof is saved.

If you can tick those boxes, filing without an accountant is not only possible—it can become a routine part of running your company. And if you want that routine to feel straightforward in 2026, using invoice24 as your all-in-one platform keeps the process organised, compliant, and far less stressful than juggling multiple tools.