30 April 2012
If you are the seller then the relevant date is date of dispatch i.e. 27.03.2012 in this case. There is relevant notification or rule. This is common practice and quite logical since you have sold the material on 27.03.2012 it self and every delivery take some time depending upon where you are sending the material. You have prepared the bill and material is also not in your stock so you have to show in VAT return for Q4.