We'd like to use Google Analytics cookies to see how our website is used. See our cookie notice.

Skip to content
Taxley Taxley.
Get started

Step by step

How to submit your Corporation Tax return online, step by step

You can submit your Corporation Tax return (CT600) online with Taxley in seven steps: create an account, enter your company details, profit and loss and balance sheet, check the Corporation Tax we calculate, review the iXBRL accounts we prepare, declare and pay the one-off fee, submit to HMRC with your own Government Gateway login, then check HMRC accepted it. Preparing is free; you pay only when you file.

Start your return See prices Check if Taxley suits your company

Last reviewed

Time
Depends on how ready your figures are; your work saves as you go
Difficulty
Straightforward companies
Tools you’ll use
A Taxley account · Government Gateway login (to file with HMRC)
Have ready
Company figures (profit and loss and balance sheet) · Company UTR · Company registration number (CRN)

The process

Submit Corporation Tax return to HMRC in seven steps

Taxley files your CT600 to HMRC online, with your own Government Gateway login, and then files your accounts at Companies House online, from the same filing page.

Want to see each screen first? Read how to file your CT600 and Companies House accounts, step by step with screenshots.

  1. Step 1: Create an account and start a filing

    Sign up, then start a new filing. Choose your accounts type — micro (FRS 105) or small (FRS 102 §1A) — and your accounting period.

  2. Step 2: Enter company, P&L and balance sheet

    A guided, saveable wizard captures your company details (CRN, UTR, registered office), your business P&L (income — trading turnover or rental, allowable expenses, finance costs) and what the company owns and owes. You can also import a trial balance exported from your bookkeeping software as a CSV or Excel (.xlsx) file, and check how each account is mapped before it is applied. You can leave and resume anytime.

  3. Step 3: We work out your Corporation Tax

    Taxley works out your taxable profit and Corporation Tax from the same figures as your accounts — the right rate for your profit level, with marginal relief applied automatically — and shows a line-by-line schedule you can check.

  4. Step 4: We prepare your accounts

    Taxley produces your statutory accounts (FRS 105 or FRS 102 §1A) and tax computations, and validates everything automatically before you see it. Behind the scenes, this means generating the inline XBRL (iXBRL) files HMRC requires, tagged to the FRC taxonomy — validation fails loudly if anything is wrong.

  5. Step 5: Declare and pay

    Confirm the director declaration (CT600 boxes 975/980/985) and pay the one-off filing fee securely via Stripe. Nothing is charged while you prepare or preview; you pay after confirming the finished return, before it can be submitted to HMRC. The fee covers filing with HMRC and filing your accounts at Companies House.

  6. Step 6: Submit Corporation Tax return to HMRC

    Submit your CT600 + accounts to HMRC with your own Government Gateway login — filing is live. Every return is checked against HMRC's CT600 schema and a set of HMRC's business rules before it is sent, and you can run a test with HMRC's test service first, which files nothing. Then file the accounts at Companies House from the same filing page, using your company's Companies House authentication code, at no extra cost. Companies House filing covers the accounts Taxley prepares. Taxley doesn't file uploaded accounts, other accounts Companies House already has, first accounts for a period that doesn't start on the incorporation date, or a community interest company's accounts, which go to Companies House with a community interest company report. The accounts must also end within 7 days of the accounting reference date Companies House holds; if they don't, Taxley can't file them there, and the filing page says what to do (file earlier accounts first, change the date where that's still allowed, or contact support).

  7. Step 7: Check HMRC accepted your return

    Your Taxley filing page shows “Accepted by HMRC” with the date and time, and Taxley emails you HMRC’s correlation ID to keep for your records. If HMRC rejects the return, the email says what HMRC reported so you can correct it and resubmit at no extra cost — your deadline still applies. Download copies of everything filed, with a full audit trail. Filing is separate from paying: pay any Corporation Tax due to HMRC yourself.

What gets filed

Does Taxley create the iXBRL accounts and tax computation for you?

Yes. Taxley builds the CT600, the Corporation Tax computation and your micro-entity (FRS 105) or small-company (FRS 102 Section 1A) accounts in iXBRL from the figures you enter, and builds them again when you change a figure. It runs a format check on them before you file, so you don't tag anything yourself. You can upload your own iXBRL accounts instead.

  • CT600 return

    The Company Tax Return itself — every box worked out from your figures and checked before it is sent.

  • iXBRL accounts

    FRS 105 / FRS 102 §1A

    Your company’s statutory accounts, tagged with the FRC taxonomy so HMRC’s systems can read every figure.

  • Tax computation

    How your accounts profit becomes taxable profit and the tax due — rates, marginal relief and adjustments.

Plus your HMRC receipt and a full audit trail, kept in your account.

Worked example

What does filing look like for a typical small company?

Take a fictional company with a year ending 31 March 2026, no associated companies and taxable profits of £40,000. Its Corporation Tax is £7,600, at the 19% small profits rate, because its profits are no more than £50,000. You see that figure in Taxley before you pay anything.

Corporation Tax for the year
£7,600
Pay HMRC by
1 January 2027
File the CT600 with HMRC by
31 March 2027
File accounts at Companies House by
31 December 2026

In Taxley you enter the year's figures once. Taxley prepares the CT600, the tax computation and the iXBRL accounts from them, and you check each one. When you file, the return goes to HMRC with your Government Gateway login and the same accounts go to Companies House, for one fee. The deadline calculator and Corporation Tax calculator work out the same figures for your own company.

Before you start

Useful to read first

Frequently asked questions

Which accounting periods can Taxley file?

Taxley files returns for UK-resident micro and small companies, including older years back to accounting periods that started on 1 April 2020.

What do I need before I start?

The company's figures for the period (profit and loss account and balance sheet), its Unique Taxpayer Reference (UTR), its company registration number and the company's Government Gateway login to file with HMRC. To file the accounts at Companies House, you also need the company's 6-character authentication code.

Can a first-time director with no accounting knowledge file with Taxley?

Yes, if the company's affairs are straightforward and you have its records. Taxley fills in the company's details from the Companies House register, can bring in last year's figures from the accounts filed there, guides you through plain steps, works out the tax, prepares the accounts and checks the return before you pay, flagging figures to review. You stay responsible for the figures.

What if my company's accounting period is longer than 12 months?

Taxley splits it into the two accounting periods HMRC needs and prepares both CT600 returns. You enter your figures once, and it is one filing with one fee.

What happens next year?

Once your return is filed, press “Prepare next year's return” on its page. The new return starts with the company's details filled in and this year's closing balance sheet as its opening position, so you don't type last year's figures again.

Can I ask a question about my return?

Yes. Use “Help with this return” on your filing page. Your question reaches Taxley support linked to that return, so we know which one you mean. We can explain how Taxley works, but we can't give tax advice.

How does payment work?

Preparing and previewing is free. When you're ready, you confirm the director declaration and pay one fee for the return through Stripe, before the final filing is produced. The fee also covers filing the accounts at Companies House. The company pays any Corporation Tax due to HMRC itself; Taxley doesn't take tax payments.

How do I know HMRC accepted my return?

Your filing page shows “Accepted by HMRC” with the date and time, and Taxley emails you HMRC’s correlation ID to keep. If HMRC rejects the return, the email says what HMRC reported so you can correct it and resubmit; your deadline still applies. Acceptance means HMRC received a valid return, not that it has checked your figures.

Good to know: Corporation Tax returns are filed live to HMRC using your own Government Gateway login — paying your Corporation Tax is always done by your company directly to HMRC. Companies House accounts filing is live too: once the return is paid and the accounts are finished, press “File accounts at Companies House” on your filing page. You'll need your company's authentication code, which you save once on the company page. The service is still maturing, so review the flagged figures carefully before you file.

Ready to prepare your return?

Create a free account and only pay when you file.

Start your return
  • Free to prepare
  • No card until you file
  • Export or delete your data anytime