I am preparing the tax return for my second accounting period. It is for just few days. The only transaction I have is a credit note towards a purchase invoice. It looks like a purchase, but with money comming in, not out. Now, in the P&L a have only cost of sales and it is positive number.
Its probably a good idea to run this past your accountant to make sure its right. If you have received a refund though and not made any purchases then a positive purchase balance sounds right to me