Standard return: file every CT600 for your accounts period
Short version. Standard return files every CT600 this accounts period needs as new returns: one for 12 months or less, two for a longer period. Use it when HMRC has no CT600 yet for this accounts period. It is the right choice for most filings.
Go to the steps and entry details
On this page
New returns onlyAny period up to 18 monthsWhere you see it: Company Profile & Period › Filing purpose
Standard return files every CT600 this accounts period needs as new returns: one for 12 months or less, two for a longer period.
- For an accounts period of 12 months or less, it files one CT600 for those dates.
- When your accounts period ends more than 12 months after it starts, even by one day, it files two CT600s. The first covers the first 12 months and the second covers the rest. The dates are shown under Filing purpose before you continue. How the dates are split
- Every return is new. Nothing already at HMRC is changed. To correct a return, use an amendment instead.
- With Enter my figures once, you enter the figures for the whole accounts period once and we share them between the two returns by the number of days. How figures are shared
- Your full accounts go to HMRC with each CT600. If you also choose Companies House, the same accounts are filed there.
Is this the right option for you?
Use it if all of these are true
- HMRC has no CT600 for any part of this accounts period yet.
- You are filing for the first time for this period, not correcting a return.
- Your Corporation Tax dates match your accounts dates, or HMRC's first return ends on a date you can enter under First CT600 ends.
Do not use it if
- HMRC already has your first CT600 with the full accounts, and only the second is outstanding.Use instead: File only the remaining CT600
- You filed a return with us and need to correct it.Use instead: How to amend a CT600
- A return for this period was filed elsewhere and needs correcting.Use instead: Amending a CT600 filed elsewhere
- HMRC says your Corporation Tax period starts later than your accounts, for example a dormant company that started trading.Use instead: Set different CT600 dates
Common mistake: choosing File only the remaining CT600 when nothing has been filed
If neither return has been filed, File only the remaining CT600 is the wrong choice. It files the second return only and treats the whole year's figures as earned in its short dates. For a one-day second return, a full year's profit is taxed at the 25% main rate. Standard return files both returns and shares the figures between them.
File only the remaining CT600 with full-year figures
- Returns filed
- Second only
- Profit taxed in a one-day return
- £9,125
- Corporation Tax
- £2,281.25
Standard return with the same figures
- Returns filed
- Both
- Return 1 profit at 19%
- £9,100
- Return 2 profit at 19%
- £25
- Corporation Tax for both returns
- £1,733.75
More help: GOV.UK: Corporation Tax rates and short periods · Marginal relief explained
Why a long accounts period has two returns
A Corporation Tax accounting period cannot be longer than 12 months. When your accounts cover a longer period, HMRC needs one return for the first 12 months and another for the rest. A period that runs from 31 May 2025 to 31 May 2026 is 366 days, so it needs two returns, even though it is only one day over 12 months. This often happens when the previous accounts ended a day earlier than the usual year end.
Each return is taxed on its own dates. The first return gets the full £50,000 and £250,000 profit limits because it covers 12 months. The second gets limits reduced to its number of days.
More help: GOV.UK: Corporation Tax accounting periods · When does a Corporation Tax accounting period end? · Time apportionment or actual figures
Worked example
- Company
- Alder Example Ltd
- Previous accounts
- Ended 30 May 2025
- This accounts period
- 31 May 2025 to 31 May 2026 (366 days)
- First CT600
- 31 May 2025 to 30 May 2026. Not filed yet
- Second CT600
- 31 May 2026 to 31 May 2026. Not filed yet
- Figures for the whole period
- Turnover £142,350, staff costs £54,750, other charges £78,475
The company and all figures on this page are fictional.
Before you start
- Your accounts
- The figures and balance sheet for the whole accounts period.
- Both return dates
- If HMRC has issued a CT603 notice, check its dates match those the wizard shows. Matching your dates to HMRC
- Company UTR
- Ten digits, on letters from HMRC. Where to find your UTR
- Government Gateway details
- The user ID and password for your company's HMRC account. Setting up a Government Gateway account
- Companies House authentication code
- Only if you are filing the accounts there too. Where to find it
The company and all figures on this page are fictional.
Step by step
Start a new filing
- Dashboard, company card
- Click New filing. If you see Resume filing, click the small arrow beside it and choose Start new filing →
- Confirm the company
- Tick the confirmation box, then click Continue with this company →
Company Profile & Period
- Accounting period
- 31 May 2025 to 31 May 2026A note headed Extended accounting period. confirms that two returns will be prepared.
- Special tax regimes
- No
- What are you filing?
- HMRC CT600, or Companies House & HMRC CT600 if the accounts also need filing at Companies House
- Filing purpose
- Standard return
- My HMRC Corporation Tax period is different from my statutory accounts period.
- Leave untickedTick it only if HMRC’s Corporation Tax period starts on a different date from your accounts.
- Change CT600 split date
- Leave as shownThe dates show as 31 May 2025 to 30 May 2026 · 31 May 2026 to 31 May 2026. Open it only if HMRC's first return ends on a different date.
- Trading status
- ActiveThe form starts on Dormant, so make sure you change it.
- How do you want to enter your figures?
- Enter my figures onceChoose Enter figures separately only if you have your own figures for each return. Separate figures
- What the company does
- Trading
Click Next →.
Financial Data
Enter the figures for the whole accounts period. Do not split them yourself.
- Previous year
- Last year’s figures, from your previous accountsRequired before you continue. Figures from Companies House fill in where available. Check them, and enter 0 where a line had no amount.
- Turnover
- 142350Box 145
- Cost of raw materials and consumables
- 0
- Staff costs
- 54750
- Other charges
- 78475
- Company tax type
- Standard companyFor a long period it is labelled “Company tax type (both returns)”.
- Balance sheet
- Your balance sheet at the end of the accounts period
- Average number of employees
- Your average number, or 0
If a dividend, gain or capital purchase belongs to one date, an allocation panel asks which return it belongs to. Click Next → when every section is complete.
More help: Amounts that belong to one date
Review & file
The Corporation tax due card shows the total for both returns. For Alder Example Ltd:
Corporation tax due£1,733 .75On taxable total profits of £9,125 at 19.0% · small profits- Optional
- Click Preview your documents (free) to check both returns first
- Subscribe
- Click Unlock Filing and complete payment
- Continue
- Click Continue to submission
Filing credentials
- Corporation Tax UTR
- Your 10-digit UTR
- Gateway User ID
- Your Government Gateway user ID
- Gateway Password
- Your Government Gateway password
- Authentication code
- Only shown if you chose Companies House as well
- Select the director submitting this return
- The director’s name
- Accounts approval date
- The date the directors approved the accountsWhat to enter
- Declaration
- Tick it
Click Submit to HMRC, or Submit to HMRC & Companies House.
More help: If HMRC rejects your sign-in details
After you submit
Under Gateway submissions, the filing page lists both returns, each marked as a new return, for example "Return 1 of 2". Each shows Accepted once HMRC confirms it. HMRC usually replies within a few minutes, but it can take longer.
Each return has its own Corporation Tax payment deadline. The Review & file page shows the dates.
More help: Filing statuses explained · Deadlines for two returns · Paying your Corporation Tax
Sample outcome
Not the right option?
Open the guide for the option that matches your filings.
Looking for a different field or step? See all filing wizard guides →
Official sources
- GOV.UK: Corporation Tax accounting periods
- GOV.UK: Corporation Tax rates
- Corporation Tax Act 2009, section 10
- HMRC Company Taxation Manual CTM01405: apportionment
- GOV.UK: Company Tax Returns
Whether this route matches your filings is for you to decide, yourself or with your accountant.
Example companies and figures are fictional. Field names match the filing wizard as of 12 October 2026.