30 June 2016
Hi, You have collected VAT in May when you were not registered, any law doesn't permit to collect taxes without being registered, if you have collected you should pay to department as soon has you have registered, also you need to inform your customer about your registration details so that he can claim Input credit of VAT.
30 June 2016
when you apply for the vat registration then you have to mention in the application that i am started the business in may then on certificate show date of liability - may -16 date of registration of vat- june-16