A company that is registered in the Companies Register, even if it has not started its activity in the year of its registration, since you have legal personality and have the status of a Corporation Tax payer, you are obliged to file a tax return for this tax period tax corresponding to that year, even if this tax return corresponds to an inactive entity.
To be taken into account:
Companies with a commercial form, as they are not duly registered, must pay tax on the income allocation system and not on Corporation Tax. Under no circumstances are civil companies considered.
If the company is not registered in the Public Register at the end of the financial year, having started the activity, it must pay tax and comply with the obligations corresponding to an entity in the income allocation regime.
Therefore, these companies will only be liable to Corporation Tax if at the end of their financial year they are registered in the corresponding Public Register.