You must keep full and accurate records of your business from the very start. You need to do this whether you prepare the accounts yourself, or, have an Accountant do it. The records you keep must be sufficient to enable you to make a proper return of income for tax purposes if you are a sole trader and comply with Companies Law if you are a Company. Examples of records to keep:
How long do I need to keep records?
You must keep your records for a period of six years