No, if you say you need the information for tax purposes (say) then the user will complain to the data protection authorities. These authorities will then accept or reject the complaint, and if accepted will help you to come into compliance.
The trouble is, that's an assumption on your part, and it might not be a valid one. We have no idea yet how 28 different regulatory authorities will handle this sort of situation, or how much of an effort they will expect controllers and processors to make on their own if they are to receive the benefit of the doubt. And even if everything you assume proves to be correct, any formal interaction with authorities is stressful and expensive for a small business with limited time and resources available, and being confident that you aren't doing anything wrong in the first place is obviously preferable.
