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Filing wizard guides
Short version. Each guide here explains one choice in the filing wizard, or one situation from start to finish. Every guide says who the choice is for, when not to use it, and the exact fields to fill in, with a fictional example and its tax result. Look up the screen you are on, or the situation that matches your company.
On this page
Guides by wizard screen
Screens are listed in the order the wizard shows them. Each card states exactly what that choice files.
Company Profile & Period
Filing purpose
Which filing option do I need?Filing purpose decides which CT600s for this accounts period are sent, and whether each one is a new return or an amendment.Standard return: file every CT600 for your accounts periodStandard return files every CT600 this accounts period needs as new returns: one for 12 months or less, two for a longer period.File only the remaining CT600File only the remaining CT600 submits only the second CT600 of a long accounting period. It does not file, change or resend your first CT600.
My HMRC Corporation Tax period is different from my statutory accounts period.
How do you want to enter your figures?
Enter my figures once: how figures are shared between two CT600sEnter my figures once uses one set of figures for your accounts and your CT600s. When there are two CT600s, recurring income and costs are shared between them by days, and each amount on an allocation panel follows the split you confirm.Enter figures separately: separate Companies House and CT600 figuresEnter figures separately uses your statutory accounts figures for the accounts and your own prepared figures for each CT600. Nothing is shared between the returns by days, and the allocation panels are not shown.
Financial Data
Guides by situation
Each situation guide follows one fictional company through every screen.
Accounts period longer than 12 months
Corporation Tax dates differ from the accounts dates
Dormant company started trading: accounts and CT600 datesYour accounts cover the whole period, and one CT600 starts on the date trading began when HMRC shows that later start. Nothing is filed for the dormant months, and the full accounts go with the return.Wrong HMRC Corporation Tax period dates: how to correct themCheck and correct HMRC's Corporation Tax dates before you file, then file new returns for the dates HMRC confirms. A date typed into filing software does not change HMRC's record, and an amendment cannot move the dates of a return HMRC already holds.Changing your company year end and Corporation Tax periodAfter a year-end change at Companies House, enter the new accounts period and file the CT600s it needs: one for 12 months or less, two for a longer period up to 18 months.First CT600 when trading started after incorporation: which accounts to attachYour first CT600 starts on the date HMRC shows, usually when trading began, but the full accounts from incorporation go with it. Costs from before trading stay in those accounts and are not entered a second time.
Amendments
Correct a CT600 you filed with us: Amend this filingAmending a return you filed with us sends each CT600 from that filing to HMRC as an amended return when you tick HMRC, and sends accounts to Companies House when you tick Companies House. It does not file a new return or change the period dates.File revised accounts at Companies House after an accepted filingRevised accounts replace the accounts Companies House accepted for the same period, with a revised accounts statement and the date the directors re-approved them. They do not change the period, and they do not amend your CT600 unless you also tick HMRC.
What you file and where
How far back can a company file an overdue CT600?Each overdue accounts period is its own filing in the wizard. File them one at a time, oldest first, each with that period's own dates, figures and filing destination.CT600 box 55: using estimated figures in a Company Tax ReturnTicking box 55 tells HMRC that the return contains an estimated figure. It does not change any figure or the tax, and it does not send the final figures later for you.
Company status
Claiming pre-trading expenses on your Corporation Tax returnQualifying pre-trading expenditure deducts qualifying costs from before trading began in the tax computation for the period trading started. It does not change your accounts and has no CT600 box of its own.Final CT600 when your company has stopped tradingThis route files the final CT600 for the Corporation Tax period that ends on the day the trade permanently stopped. It does not tell HMRC the company is dormant, and it does not close the company.How to file a CT600 after your company stops tradingThis route files a CT600 for a Corporation Tax period that starts after the trade permanently stopped, with bank interest in box 170 and post-cessation receipts in box 205. It does not file or change the final trading return.
Why is my tax this amount?
Why does my Corporation Tax show 25%? Reading the Corporation tax due lineThe Corporation tax due card shows tax on your taxable total profits. From 1 April 2023 the rate is set by those profits and the £50,000 and £250,000 limits for the return’s dates, not by turnover.Associated companies and your Corporation Tax rateThe number you enter in Associated companies divides the £50,000 and £250,000 Corporation Tax limits by that number plus one, which can change the rate your profit is taxed at but never the profit itself.CT600 box 285: claiming trading losses against total profitsTrading losses to claim against total profits (box 285) sets how much of your eligible brought-forward trading losses reduces this return’s total profits: leave it blank for the maximum shown, or enter 0 to claim nothing.Director’s loan not repaid within nine months: section 455 tax and CT600A explainedDirector’s loans and section 455 tax adds a CT600A to this CT600 for prepared loans made in the period and still outstanding at its end, and adds the section 455 tax to the total tax reported.
Other kinds of organisation
Property management company CT600: how to use box 4 code 7Choosing Property management company under Company tax type files code 7 in box 4 of every CT600 in the filing, for an active company only. Code 7 does not change the tax, and the dormant journey does not offer it.Companies limited by guarantee: filing the CT600 and accountsA company limited by guarantee files through the ordinary company route: a CT600 with a tax computation for an active company, and micro-entity accounts showing members' funds with no share capital, to HMRC, Companies House or both. A charitable company claiming exemption uses the separate CT600E route.How to prepare CIC accounts and a CIC34 report for Companies HouseThis route files your CIC’s CT600 and accounts with HMRC and, when you choose Simplified or Detailed, builds a ZIP of your accounts and CIC34 report for you to upload. It does not file anything with Companies House.How to file a charity or CASC Corporation Tax return with CT600EThis route files a CT600 with CT600E pages with HMRC for a charity or CASC claiming exemption on all its income and gains. It does not file anything with Companies House or a charity regulator, and it does not prepare your accounts.How to file a CT600 for an unincorporated club or CASCThis route files the CT600 returns of an unincorporated club or registered CASC with HMRC, adding CT600E for any return that claims exemption. It does not file anything with Companies House or prepare the club’s accounts.
Getting the figures in and getting through submission
How to import Xero, QuickBooks, Sage Accounting or spreadsheet data for a CT600Importing fills only the Financial Data figures you approve from a Xero, QuickBooks, Sage Accounting or spreadsheet report. It does not change your dates, submit anything or divide one-date amounts between two returns for you.How to prepare and import your own Excel or CSV accounts spreadsheetImporting your own spreadsheet fills only the Financial Data figures you approve from your Excel or CSV accounts. It does not need accounting software, change your dates or submit anything.Save your Company Tax Return and finish it laterSaving progress keeps your unfinished filing in your account, so you can resume it later from any device where you sign in. It does not submit anything to HMRC or Companies House.Paying your Corporation Tax after you fileFiling your CT600 does not pay the tax. You pay HMRC directly, by each return's payment deadline, using the 17-character payment reference for that return's accounting period.Setting up a Government Gateway account to file Corporation TaxGateway User ID and Gateway Password are the Government Gateway sign-in details for the HMRC business tax account that has Corporation Tax added and activated for this company.Where to find your company UTR for Corporation TaxCorporation Tax UTR is the 10-digit Unique Taxpayer Reference HMRC gave your company for Corporation Tax. It is not a personal UTR or the Companies House company number.Companies House authentication code: where to find or request itAuthentication code is the 6-character company authentication code Companies House issues to your company. It is needed only when Companies House is a filing target.HMRC rejected my sign-in details but they are correctWhen HMRC refuses your CT600 with an Authentication Failure, that return was not filed. This guide finds which of five causes it is and shows how to send the return again.
Official sources
Each guide links the HMRC, Companies House or legislation pages it relies on. These are the general starting points:
- GOV.UK: Company Tax Returns
- GOV.UK: Corporation Tax accounting periods
- Companies House: file your annual accounts
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