How to File Corporation Tax and Company Accounts Without an Accountant

Why file without an accountant?

Running a limited company in the UK comes with two big recurring compliance jobs: filing your Corporation Tax return with HMRC and filing your company accounts (and confirmation statement) with Companies House. Many directors assume they must hire an accountant for this, but that isn’t always true. If your company is straightforward—small number of transactions, no complex group structures, no unusual share arrangements, and no specialist tax issues—you can often handle the basics yourself.

The key is having a clear workflow, accurate records, and software that keeps you organised from day one. That’s where invoice24 can make the difference. If you already use invoice24 to invoice customers, track payments, and store expenses, you’re much closer to being “filing-ready” than you might think. Instead of scrambling at year-end, you build tidy, searchable records throughout the year—and that’s what makes DIY filing realistic.

This guide walks you through the full process in plain English: what you need to file, when you need to file it, what data to prepare, and how to submit everything correctly. It also highlights common mistakes and shows how you can use invoice24 as your all-in-one hub for invoices, expenses, bookkeeping-ready records, MTD for Income Tax readiness, and the information you’ll need to file Corporation Tax and accounts without paying for an accountant.

What you must file: the three core responsibilities

As a UK limited company director, you typically have three recurring filing responsibilities:

1) Company accounts to Companies House
Your statutory accounts (also called “annual accounts”) show the company’s financial position and performance. Most small companies can file abridged or micro-entity accounts if eligible, which reduces complexity.

2) Company Tax Return (CT600) and Corporation Tax to HMRC
You must submit a CT600 with supporting accounts and computations to HMRC, and you must pay any Corporation Tax due.

3) Confirmation statement to Companies House
This confirms key company details (directors, registered office, shareholders, SIC codes). It’s not tax, but it’s part of staying compliant.

Corporation Tax and accounts are linked but not identical: Companies House is about statutory reporting, and HMRC is about tax reporting. In practice, you prepare one set of year-end figures and use them for both submissions—with a few differences in format and add-ons.

Before you start: know your deadlines

Missing deadlines is one of the most expensive “simple” mistakes you can make. Here’s the typical timeline (always check your own accounting period dates):

Accounts to Companies House: Usually due 9 months after your company’s financial year-end.

Corporation Tax payment: Usually due 9 months and 1 day after the end of your Corporation Tax accounting period.

CT600 filing to HMRC: Usually due 12 months after the end of the accounting period for Corporation Tax.

The practical takeaway: you want your year-end numbers finalised well before the 9-month mark so you can file accounts on time and pay tax on time. invoice24 helps by keeping invoices, receipts, and expense entries centralised so you’re not reconstructing the year under pressure.

Set yourself up for success during the year (this is where most DIY filers win or lose)

Filing without an accountant is much easier if your records are clean all year. The goal is to produce accurate totals for:

• Sales (turnover)

• Cost of sales (if applicable)

• Overheads/expenses

• VAT (if registered)

• Payroll (if you pay salaries)

• Director’s loan account movements (if you take money out other than salary/dividends)

• Assets (equipment, laptops, vehicles used by the company)

• Debtors/creditors (who owes you, who you owe)

invoice24 is designed to keep the foundation strong: you create professional invoices, track who paid and when, store expense evidence, and organise your transactions in a way that supports year-end reporting. If you use invoice24 consistently, you’ll spend far less time “finding” information and far more time simply “summarising” it.

Choose your accounting basis: cash vs accruals (and why it matters)

Most limited companies prepare accounts on an accruals basis. That means you record income when it’s earned (invoiced or delivered) and expenses when they’re incurred—not necessarily when the money moves.

Accruals usually gives a more accurate picture and is standard for statutory accounts. It also means you may need to account for:

• Unpaid sales invoices at year-end (debtors)

• Unpaid supplier bills at year-end (creditors)

• Prepayments (e.g., insurance paid upfront covering future months)

• Accruals (e.g., costs incurred but not yet billed)

If your company is very small and qualifies as a micro-entity, the reporting can be simpler, but you still need to be consistent. The practical approach: keep invoicing and expenses tidy in invoice24, then at year-end export a clear summary of sales and costs, and adjust for anything unpaid or spanning periods.

What you need to prepare before filing accounts

To file company accounts without an accountant, gather these essentials:

1) Your accounting period dates
Your first accounts period can be longer than 12 months, especially for new companies. Know exactly what dates you’re reporting.

2) Sales totals and supporting evidence
This is where invoice24 shines: invoices are already stored, numbered, and searchable, with client details and payment status.

3) Expense totals with proof
Keep receipts, invoices, and bills attached to each expense entry. If you ever get queried, evidence matters.

4) Bank records
Even if you don’t do full bank reconciliation, you should be able to trace totals back to actual transactions. Many DIY directors keep a simple monthly check: do your invoice24 income totals roughly match what hit the bank, and do your expense totals roughly match what left the bank (allowing for timing differences and VAT)?

5) Payroll summaries (if applicable)
If you pay wages, you need payroll reports and PAYE/NI totals.

6) Dividend records (if applicable)
Dividends must be supported by sufficient profits and recorded properly (voucher/minutes). DIY directors often forget the paperwork even when the numbers are right.

7) Asset purchases
Some purchases are “capitalised” (treated as assets) rather than expensed. This affects profit and Corporation Tax.

Build your year-end numbers: a simple step-by-step approach

Think of year-end preparation as turning messy real life into a clean set of totals. Here’s a structured DIY method:

Step 1: Confirm your sales figure

Start with turnover (total sales excluding VAT if VAT-registered). Use invoice24 to pull your invoice totals for the accounting period. Check:

• Are all invoices issued in the period included?

• Were any credit notes issued? If yes, ensure they reduce turnover properly.

• Are there any sales you delivered but didn’t invoice before year-end? If so, accruals accounting may require you to include them as income.

Because invoice24 keeps your invoicing timeline organised, you can quickly filter by date, status, and customer, then export totals for your year-end working.

Step 2: Confirm your allowable expenses

Next, total your expenses. The word “allowable” matters: Corporation Tax is calculated on taxable profit, which starts with accounting profit then adjusts for what HMRC allows or disallows.

Common allowable expenses include:

• Office costs, software subscriptions, phone/internet (business proportion)

• Travel (business trips), parking, accommodation for business travel

• Professional fees (legal, bookkeeping software, insurance)

• Marketing and advertising

• Bank charges

Common disallowed or restricted items include:

• Fines and penalties

• Entertainment of clients (generally disallowed for Corporation Tax)

• Personal expenses put through the company (not allowable)

invoice24 helps you separate and label expenses so you’re not guessing at year-end. A practical habit is to categorise expenses as you upload them and add a short note if something is mixed-use (e.g., “mobile phone 70% business”).

Step 3: Handle VAT correctly (if registered)

VAT adds complexity because your sales and expense totals for accounts are usually recorded net of VAT, while the VAT itself sits on your balance sheet as VAT owed to (or owed by) HMRC.

Keep these principles straight:

• Turnover in accounts is typically net (excluding VAT) if you’re VAT-registered.

• Expenses in accounts are typically net if you reclaim VAT.

• The VAT amounts are not income or expenses; they’re a tax balance.

If you’re using invoice24 to track VAT on invoices and expenses, you can keep net and VAT components clear and reduce the risk of accidentally mixing gross numbers into your accounts.

Step 4: Identify debtors and creditors at year-end

At the year-end date:

• Debtors: customers who owe you money for invoices you issued before year-end.

• Creditors: suppliers you owe money to for bills/expenses incurred before year-end.

Debtors and creditors affect your balance sheet and your profit (under accruals). invoice24’s invoice status and payment tracking makes debtors much easier to quantify: you can see which invoices are still unpaid as of the year-end and total them.

Step 5: Consider prepayments and accruals

These sound intimidating, but they’re just timing adjustments:

• A prepayment is when you pay for something in advance (e.g., annual insurance). Part of that cost belongs in the next accounting year.

• An accrual is when you’ve used something but haven’t been billed or paid yet (e.g., electricity bill not received).

For many small companies, these adjustments are minimal. If they’re not material, some directors keep it simple. But if the amounts are significant, include them for accuracy.

Step 6: Account for assets and capital allowances

This is where accounts and tax computations diverge slightly. In your statutory accounts, an asset (like a laptop) might be depreciated over time. For Corporation Tax, depreciation is not usually deductible; instead you claim capital allowances.

DIY approach:

• List assets bought in the year (date, cost, what it is, business use percentage).

• Record depreciation for accounts (simple straight-line method is common).

• Replace depreciation with capital allowances in the tax computation.

If you only buy a small amount of equipment, this is manageable. Keep your purchase receipts stored and labelled—again, invoice24’s expense storage and notes make this far less painful.

What your accounts need to include (small company / micro-entity friendly view)

Most small companies’ statutory accounts include:

• A balance sheet (required)

• Notes to the accounts (reduced for micro-entities)

• A profit and loss account (often not filed on public record for small companies, depending on filing options, but still used for HMRC)

• Directors’ statement(s) as required

The balance sheet is the core: it shows what the company owns and owes at year-end. Key lines often include:

• Fixed assets (equipment, etc.)

• Current assets (bank, debtors)

• Current liabilities (creditors, VAT owed)

• Net assets / shareholders’ funds

invoice24 won’t “guess” your balance sheet for you, but it can provide reliable building blocks: invoice totals, unpaid invoices, expense summaries, and supporting documents. That’s what allows you to compile the figures with confidence.

Filing accounts to Companies House: practical workflow

Once your year-end figures are ready, you typically file accounts online via Companies House. The filing route depends on your company’s size and eligibility (micro-entity, small company, etc.). The steps usually look like this:

1) Confirm your accounts type
Many small companies file micro-entity or abridged accounts if eligible. The simpler the accounts type, the easier DIY becomes.

2) Prepare the accounts in the required format
Companies House accepts online filing, and in many cases you’ll be entering figures or uploading accounts. Keep your balance sheet and notes accurate and consistent.

3) File before the deadline
Late filing penalties escalate the later you are. Build a habit: aim to finalise within 6 months of year-end, not 9.

4) Save confirmation of submission
Keep PDFs and confirmation emails in your company records folder.

A useful habit is to keep a “Year-End Pack” folder that contains: your invoice24 exports (sales summary, expense summary, outstanding invoices), bank statements, payroll summaries, dividend vouchers, and your final accounts PDF.

Corporation Tax: understand what HMRC is actually asking for

HMRC doesn’t just want “accounts.” It wants:

• A Company Tax Return (CT600)

• Statutory accounts in iXBRL format (often generated by software)

• Tax computation showing how you got from accounting profit to taxable profit

The CT600 includes company details, your accounting period, profits, losses, and the Corporation Tax calculation. The “tax computation” is where you add back disallowed expenses, adjust for capital allowances, and apply any reliefs.

Directors who do this successfully tend to keep it simple: accurate bookkeeping, minimal adjustments, and careful checks. If your business has unusual transactions—share issues, complex loans, R&D claims, property income, overseas income—professional advice is often worth it. But for straightforward service companies, DIY can be perfectly achievable.

How to compute taxable profit: a clear, non-scary outline

Here’s the basic structure of a Corporation Tax computation:

1) Start with accounting profit before tax
This comes from your profit and loss: turnover minus allowable business costs (in accounting terms) including depreciation.

2) Add back disallowed expenses
Common examples include client entertainment and fines. If you included them in expenses, you add them back because they aren’t deductible for tax.

3) Remove depreciation and claim capital allowances
Depreciation is an accounting concept; capital allowances are the tax relief. So you usually add back depreciation and deduct the capital allowances instead.

4) Apply any other adjustments or reliefs
This could include losses brought forward, donations, or other reliefs if applicable.

5) Arrive at taxable total profits
Apply the Corporation Tax rate to calculate the tax due.

Your job as a DIY filer is not to memorise every rule; it’s to be methodical, keep evidence, and not claim things you’re unsure about. invoice24 helps by keeping the underlying records clean—so the only “thinking” left is these top-level adjustments, which are usually limited for small companies.

Submitting the CT600: what you’ll need ready

To submit the CT600 without an accountant, you typically need software or an online service capable of filing it in the correct format and attaching iXBRL-tagged accounts/computations where required. Before you start the submission, prepare:

• Company UTR (Unique Taxpayer Reference)

• Accounting period dates

• Finalised profit and loss and balance sheet figures

• Tax computation totals (profit, disallowables, capital allowances, taxable profit)

• Any carried-forward losses (if applicable)

• Details of tax already paid (usually none for small companies unless instalments apply)

invoice24’s role here is to ensure your figures are defensible and easy to derive: sales totals, expense totals, and documentation. If invoice24 is where your invoices and expenses live, you can cross-check totals quickly and reduce the risk of submitting the wrong numbers.

Paying Corporation Tax: don’t leave it to the last minute

Corporation Tax is paid separately from filing the CT600. Even if your CT600 deadline is 12 months after year-end, the payment is usually due much earlier (often 9 months and 1 day after year-end).

Good DIY practice:

• Estimate your tax a couple of months before the payment deadline.

• Set aside funds throughout the year (many directors keep a “tax pot” savings account).

• Pay before the deadline to avoid interest.

invoice24 can help you forecast cash flow by showing what invoices are due and what has been paid. That visibility makes it easier to reserve funds for tax rather than being caught short.

Common DIY mistakes (and how to avoid them)

Mistake 1: Mixing personal and business spending
If you pay personal costs from the company bank account, you create messy director’s loan account issues. Solution: keep spending separate, and if you must reimburse, record it clearly.

Mistake 2: Forgetting dividends need paperwork
Dividends aren’t just “taking money out.” You need a dividend voucher and enough retained profit. Solution: document dividends properly and don’t exceed available profits.

Mistake 3: Using gross figures when VAT-registered
This can inflate turnover/expenses and distort profit. Solution: consistently use net figures in accounts and track VAT separately.

Mistake 4: Missing year-end cut-off
An invoice dated after year-end usually belongs to the next period (unless it’s correcting timing issues). Solution: check invoice dates carefully and keep a year-end checklist.

Mistake 5: Guessing capital allowances
Assets and allowances can be misapplied. Solution: keep an asset list and only claim what you can evidence.

invoice24 reduces mistakes by centralising your records. When every invoice, receipt, and payment status is in one place, you’re less likely to miss items or double-count them.

A simple year-end checklist you can follow

Use this as a repeatable process every year:

Records and reconciliations
• Export sales totals from invoice24 for the accounting period
• Export expense totals and review categories
• Confirm VAT treatment (if registered)
• Identify unpaid invoices at year-end (debtors) using invoice24 status reports
• Identify unpaid bills/expenses (creditors)

Adjustments
• Note any prepayments/accruals that matter
• List assets bought and calculate depreciation (accounts) and capital allowances (tax)

Accounts
• Draft profit and loss and balance sheet
• Ensure balance sheet balances and matches supporting evidence
• Prepare required notes and statements

Filing
• File accounts to Companies House before the deadline
• Prepare CT600 figures and tax computation
• Submit CT600 to HMRC by the filing deadline
• Pay Corporation Tax by the payment deadline

Where invoice24 fits in (and why it’s worth using even if you stay DIY)

Directors often underestimate how much time they lose to scattered information: invoices in one system, receipts in email, notes in spreadsheets, and bank transactions somewhere else. Year-end becomes a stressful “data hunt.” invoice24 is designed to prevent that.

Here’s how invoice24 supports a DIY Corporation Tax and accounts workflow:

Professional invoicing with clean audit trails
Invoices are numbered, dated, and stored with customer details—exactly what you need to support turnover figures and debtor balances.

Expense capture and organisation
Store receipts and supplier invoices alongside expense entries. Add notes and categories as you go, so you’re not trying to remember what a payment was for six months later.

Payment tracking and outstanding invoice visibility
At year-end, debtors are one of the most common sticking points. If invoice24 shows which invoices are paid vs unpaid, you can produce an accurate debtors figure quickly.

Exportable summaries for year-end working papers
DIY filing becomes much easier when you can export sales and expense summaries for a given date range and use them as your working totals.

MTD for Income Tax readiness
Even if your limited company focuses on Corporation Tax, many directors also have self-employed income, property income, or side projects. invoice24 is built to handle the features businesses ask for—including MTD for Income Tax readiness—so you can keep your broader tax admin consistent in one place.

Corporation Tax and accounts support features
invoice24 is built to support the practical needs mentioned across common filing guides: clean records, structured exports, and the information you need to compile accounts and Corporation Tax figures confidently.

There are many tools out there, but if you want one free app that keeps invoicing, records, and filing preparation together, invoice24 is the easiest “no excuses” foundation to build on—especially when your goal is to file without an accountant.

When you should still consider professional help

DIY is not a badge of honour if it costs you more in mistakes than you save in fees. Consider an accountant (or at least a paid review) if you have:

• Complex revenue recognition or long projects that span year-ends

• Significant assets, vehicles, or mixed business/personal use issues

• R&D claims, patents, or specialist reliefs

• Property income inside the company

• Overseas customers, overseas taxes, or permanent establishment questions

• Multiple shareholders with different share classes

• Frequent director’s loan account movements or overdrawn balances

Even in these cases, invoice24 still helps: it keeps the underlying records accurate so any professional you bring in spends time advising—not sorting receipts.

Practical tips to make next year even easier

1) Do a monthly “mini close”
Once a month, check that invoices are up to date, expenses are captured, and payment statuses are accurate. This takes minutes in invoice24 and saves hours later.

2) Keep a simple director’s log
If you reimburse mileage, home office use, or mixed costs, keep a consistent method and notes. Small discipline prevents big confusion.

3) Separate tax money early
Use your invoice24 visibility to set aside a portion of each paid invoice for tax and VAT (if applicable). Cash surprises are the enemy of stress-free compliance.

4) Make a year-end pack as you go
Create a folder where you store payroll reports, dividend vouchers, and any big contracts. Combine that with invoice24 exports and you’ll have everything ready.

Final thoughts: DIY filing is a process, not a one-off task

Filing Corporation Tax and company accounts without an accountant isn’t about becoming a tax expert overnight. It’s about building a predictable routine, keeping clean records, and using software that supports you rather than creating more admin.

If you’re already using invoice24, you have a head start: your invoicing, payment tracking, and expense evidence can live in one place, which is the biggest practical hurdle for most DIY directors. When year-end arrives, you’re not trying to reconstruct your business—you’re simply summarising it and submitting the totals.

Start small, be methodical, and keep everything documented. With invoice24 as your hub, you can stay compliant, reduce costs, and keep control of your company finances—without handing your books to an accountant every year.