In this section:
- PAYE for agents and advisers
- Self Assessment for agents and advisers
- VAT for agents and advisers
- Corporation Tax for agents and advisers
- Tax credits for agents and advisers
- Acting as a tax agent for a CIS contractor or subcontractor
- Capital Gains Tax basics for agents and advisers
- Inheritance Tax for solicitors and tax advisers: the basics
- Trusts for agents and advisers: first steps
- Get started with our online services for agents and advisers
Corporation Tax for agents and advisers
Many agents and advisers act on behalf of companies and deal with their Corporation Tax affairs. If you're about to start handling Corporation Tax for your clients, it makes sense to start using the Corporation Tax Online for agents service, as it will save you time and money.
From 1 April 2011, Corporation Tax liabilities, for any accounting period, must be paid electronically. And from then, for any accounting period ending after 31 March 2010, you must also file your Company Tax Returns for your clients (including supporting documentation) online.
This guide will help you set up and use the HM Revenue & Customs (HMRC) Corporation Tax Online Service. It'll also help you to choose the type of software that suits you best.
The guide also introduces some of HMRC’s useful online tools and guidance to help you manage your client’s Corporation Tax affairs.
On this page:
- Get an agent reference number
- Set up Corporation Tax Online for agents
- Manage Corporation Tax Online for agents
- The forms we'll send you
- Choose software to manage Corporation Tax online
- Useful Corporation Tax information and tools
- More useful links
Get an agent reference number
If you have not already registered as an agent, you need to do so. You do this by contacting your local Corporation Tax Office. Your tax office will provide you with a Corporation Tax agent reference number, which you need to use when setting up the Corporation Tax Online service.
Find your local Corporation Tax office
Set up Corporation Tax Online for agents
Once you have your agent reference number, you can register for the Corporation Tax Online for agents service.
You can register and enrol for Corporation Tax Online for agents through the HMRC Online Services registration page.
The registration process only takes a few minutes to complete. You'll have to:
- provide a few details about yourself
- choose a password - this must be between 8 and 12 characters, and contain at least one number (0 to 9) and one letter (a - z)
- make a note of your User ID - this will appear on screen and we'll confirm it by post within seven days
Register as a new agent user through HMRC Online Services
Once you've done this, you can file your clients' Company Tax Returns using the service.
If your client wants you to communicate with HMRC on their behalf regarding their Company Tax Returns or Corporation Tax position, you'll need to get their formal authorisation to do so. Unless you get formal authorisation, you can only file returns on their behalf.
Agent authorisation for Corporation Tax
You can set up client authorisations by using the online authorisation process or sending HM Revenue & Customs (HMRC) a completed form 64-8 signed by the client.
To set up individual authorisations online you'll need to enter two out of the following three pieces of information:
- client's Unique Taxpayer Reference (UTR)
- the postcode of their registered office
- their Company Registration Number (CRN)
Once HMRC has successfully validated the record, they’ll send a letter to your client that confirms that you've asked to set up an authorisation. It'll also include a unique authorisation code. If your client agrees with the authorisation, they should pass this code to you so that you can set up the authorisation through the HMRC Online Service. Or if they have a Government Gateway account, they can authorise you online at the Government Gateway website.
The key benefits of using the online process are:
- authorisations are processed faster, with automatic updates of the Corporation Tax system
- errors are reduced
- there's an improved audit trail of the authorisation process
Guidance on agent authorisation
Find out about the online authorisation process
Manage Corporation Tax Online for agents
You can use Corporation Tax Online for agents to file your clients' Company Tax Returns over the Internet. And if you are formally authorised by your client, you can also use the service to:
- Get instant access to your clients' Corporation Tax liabilities and payment records for each accounting period. You can see their current balance - including any interest and penalties, payments, repayments and reallocations - and view details for the last seven years.
- Change your own contact details.
Filing a return
To file returns, you can either use HMRC’s software or software developed by commercial providers.
You can file your clients' Company Tax Returns using HMRC’s free filing software. You'll need to enter the client name, UTR, CRN or Client Reference. HMRC’s software only covers:
- the CT600 form
- supplementary pages CT600A, CT600C Part 1 and Part 2 and CT600J
Commercial software packages can be used to file returns and these generally allow you to file the other supplementary pages as well.
Viewing liabilities and payments
You can find a client's latest liabilities and payments position by searching with their:
- name
- UTR
- CRN
- Client Reference
You are then able to view their Corporation Tax position for different accounting periods. You can also download your whole client list or view it online.
If your clients have a Group Payment Arrangement (GPA) in place, you can view a summary of the group's liabilities and payments made for the last five years.
Changing client and agent details
You can update contact details and addresses for communication for any clients who are incorporated businesses. If your client is unincorporated, such as a club or association, you can change details of their name, address and contact details.
You'll also be able to change your own address and contact details.
The forms HMRC will send you
When you are acting on a client's behalf, HMRC may send to you by post a number of forms during the tax year. These include:
- CT603A - a monthly list of your clients that HMRC has sent a notice to deliver a Company Tax Return (CT603)
- CT205 - return reminder
- CT209 - payment receipt, if requested
- CT210 - change of Tax Office dealing with a client
- CT211 - late filing penalties determinations
- CT214 - sending back an unsatisfactory return
- CT610 - important dates for new companies
- CT620 - acknowledgment of self assessment
HMRC won't automatically send you Company Tax Return forms because many agents and advisers use approved software versions instead. If you need these forms, you can get them by calling the CTSA Orderline on Tel 0845 300 6555. The most you can get is 50 at a time.
See the list of forms that are sent to agents by HMRC
Choose software to manage Corporation Tax online
HMRC provides free software called 'Online Tax Return - CT', which lets you file Company Tax Returns (CT600) and supplementary pages CT600A, CT600C and CT 600J over the Internet.
When you log on to HMRC Online Services, you'll be able to choose this as one of your filing options. HMRC has tested all the features of this service and provide free helpdesk support to users.
You can also buy commercial software from other suppliers that allow
you to file the return form, supplementary pages, accounts and computations
online. HMRC provides a validation service to help software companies
test their products. If they're successful, HMRC adds them to its list
of approved packages.
See a list of approved Corporation Tax Online software
More useful links
You can find general and technical guidance on managing Corporation Tax for your clients on this website.
General Corporation Tax guidance
You can access all HMRC’s general guidance, forms and returns, rates and allowances from the Corporation Tax section of this website. Areas covered include:
- Getting started with Corporation Tax
- Corporation Tax for new companies and organisations
- Forms, rates, allowances and reliefs
- Managing your Corporation Tax
- Paying Corporation Tax
- Completing and filing your Company Tax Return
- Records for Corporation Tax: what you need to keep
- Directors’ loan accounts and Corporation Tax explained
- Managing change and dealing with problems
- HMRC compliance checks, appeals, interest and penalties
- Changes to your company circumstances
- Corporation Tax for charities and unincorporated organisations
Technical guidance
Technical guidance - including HMRC staff manuals for Corporation Tax and issues related to calculating Corporation Tax liabilities - is also available.
Corporation Tax forms, manuals and detailed guidance
Marginal Rate Relief Calculator
This calculator works out how much marginal starting rate relief or marginal small companies' relief your client is eligible to claim. It will also tell you if none is due.
Find guidance on Marginal Rate Relief
