Company Tax Return (CT600) vs Annual Accounts: What's the Difference?

Company Tax Return (CT600) vs Annual Accounts: What's the Difference?

Every UK limited company has two separate annual filing obligations — one to HMRC and one to Companies House. Many directors confuse them or don't realise they need both. Here's exactly how they differ.

Quick Comparison

The CT600: Your Tax Return to HMRC

What it is

The CT600 is your Corporation Tax return. It tells HMRC:

• How much profit your company made
• How much corporation tax is due
• Any reliefs or allowances you're claiming
• Details of any other income or gains

What you submit

• The CT600 form itself (completed electronically)
• iXBRL accounts (a copy of your annual accounts in machine-readable format)
• Tax computation (showing how you calculated taxable profit)

Key points

• Filed electronically — HMRC doesn't accept paper CT600s anymore
• Must include iXBRL accounts (generated by filing software or your accountant)
• Confidential — only you and HMRC see your CT600
• Links to your tax payment obligation

Deadline

12 months after the end of your accounting period.

Example: Year-end 31 March 2025 → CT600 due by 31 March 2026.

Annual Accounts: Your Report to Companies House

What they are

Annual accounts are your company's financial statements filed at Companies House. They report:

• The company's financial position (balance sheet)
• Profit and loss (for all but micro-entities filing FRS 105)
• Notes to the accounts
• Directors' report (if required)

What you submit

For micro-entities (most small companies):

• Balance sheet only
• A few notes
• Director's signature confirmation

For small companies (FRS 102 Section 1A):

• Balance sheet
• Profit and loss account
• Notes to the accounts
• Directors' report

Key points

• Publicly available — anyone can search for your company and view the accounts on Companies House
• Micro-entities can file abbreviated accounts (less detail)
• Can be filed online or by post (online is recommended)
• Separate from the CT600 — different system, different deadline

Deadline

9 months after the end of your accounting period.

Example: Year-end 31 March 2025 → Accounts due by 31 December 2025.

First year exception: New companies get 21 months from incorporation to file their first accounts.

How They Relate

The CT600 and annual accounts are connected but separate:

Accounts feed into the CT600

Your annual accounts provide the numbers that go into your CT600. The profit figure in your accounts is the starting point for your tax computation.

iXBRL accounts go with both

When you file your CT600 with HMRC, you include a copy of your accounts in iXBRL format. You also file accounts at Companies House. The figures should be the same, but the level of detail may differ (Companies House gets the abbreviated version; HMRC gets the full version).

Different deadlines

This is where it gets confusing:

Your Companies House accounts are due 3 months before your CT600. In practice, you should prepare your accounts first, then use them to file the CT600.

What Happens If You Miss Each Deadline?

Late CT600 (HMRC)

Late accounts (Companies House)

Companies House penalties are automatic with no appeal process based on reasonable excuse (unlike HMRC).

Double penalties

If you're late with both, you pay both sets of penalties. They're from different organisations and don't affect each other.

Can I File Them at the Same Time?

Companies House accounts: standalone

You file these directly with Companies House through their WebFiling service or via software.

CT600 with HMRC: includes accounts

When you file your CT600, you include the iXBRL accounts as part of the submission. So filing your CT600 effectively files your accounts with HMRC — but not with Companies House.

You must file separately

There is no single filing that covers both. You need to:

1. Prepare your accounts
2. File them at Companies House
3. File your CT600 (with attached iXBRL accounts) at HMRC

Some software and accountants handle both filings for you.

The Confirmation Statement (Annual Return)

Don't confuse annual accounts with the confirmation statement — a third annual obligation:

The confirmation statement (formerly annual return) is a simple check that your company details are up to date. It's due annually on the anniversary of incorporation (or last confirmation statement).

For Micro-Entities: Simplified Filing

If your company qualifies as a micro-entity (which most small companies do), filing is simpler:

Micro-entity thresholds (at least 2 of 3)

• Turnover ≤ £632,000
• Balance sheet total ≤ £316,000
• Average employees ≤ 10

What micro-entities file

At Companies House:

• Balance sheet only (no P&L required)
• Minimal notes
• No directors' report

At HMRC (with CT600):

• Full accounts in iXBRL (including P&L)
• Tax computation
• CT600 form

The privacy advantage

Since Companies House only gets the balance sheet for micro-entities, your revenue and profit figures are not publicly visible. Only HMRC sees the full picture.

Practical Workflow

Here's the recommended order for filing:

1. Prepare accounts (month 1-6 after year-end)

• Gather bank statements, invoices, receipts
• Calculate profit/loss
• Prepare balance sheet

2. File at Companies House (by month 9)

• Submit abbreviated/micro-entity accounts
• Confirm they're accepted

3. File CT600 at HMRC (by month 12)

• Use the same accounts figures
• Add tax adjustments (depreciation → capital allowances)
• Calculate corporation tax
• Submit CT600 with iXBRL accounts attached

4. Pay corporation tax (by month 9 + 1 day)

• Pay before the CT600 filing deadline
• Don't wait until month 12 — the payment deadline is month 9

Taxpipe handles the HMRC side. We generate your CT600 and iXBRL accounts for HMRC submission — just £59. You'll still need to file separately at Companies House.

Frequently Asked Questions

If I file my CT600 with HMRC, does that cover Companies House?

No. Filing your CT600 submits accounts to HMRC only. You must file separately at Companies House.

Can I use the same accounts for both?

Yes — the figures should be identical. But the format may differ (abbreviated for Companies House, full for HMRC).

What if my accounts and CT600 figures don't match?

They should match. If HMRC notices a discrepancy between your CT600 and Companies House accounts, it could trigger an enquiry.

Which deadline comes first?

The Companies House accounts deadline (9 months) comes before the CT600 deadline (12 months). But the corporation tax payment deadline (9 months + 1 day) comes first of all.

Do dormant companies need both filings?

Yes. Dormant companies must file both:

• Dormant company accounts at Companies House
• Nil CT600 at HMRC (if registered for corporation tax)

Ready to file your CT600? Start with Taxpipe — we generate the CT600 and iXBRL accounts for HMRC. Just £59, 15 minutes, no jargon.

Related Articles

• What Records Do I Need for My Company Tax Return?
• Do I Need to File a CT600? When Your Company Must Submit a Tax Return
• Your First Company Tax Return — A New Director's Guide to CT600 Filing
• CT600 Deadline: When Is Your Company Tax Return Due?