Who should file company tax returns with HMRC
All business have a legal obligation to report annually the financial health of their business to the regulating authority. One of which is you must complete and submit Company Tax Return through Form CT600 with HMRC and pay Corporation Tax on profits from doing business. The profit or loss calculations for the purpose of filing company tax return is different from the profit or loss shown in your annual accounts while filing with Companies House.
In the UK, you will have to file company tax return annually, if you are registered as:
Not Incorporated but Trading
The following organisations may also need to file the company tax returns even if they're not incorporated but starts trading:
Your company or association must file a Company Tax Return if you get a notice “to deliver a Company Tax Return” from HM Revenue and Customs (HMRC). Even if your company is loss-making or you have no Corporation Tax due, you still need to declare that with HMRC.
It is worth mentioning here that the responsibility of the submitting company tax return and paying the tax on time lies with the company director - even if the company uses external professional services to prepare their accounts and financial statements.
If your business is registered as a sole trader or partnership, instead of filing company tax return, you will file self-assessment tax return.