If you use the VAT cash accounting scheme there are special rules for completing boxes 1, 4, 6 and 7 of the return. All other boxes are completed as normal.
Box 1: is the VAT on cash receipts you have had (not invoices issued)
Box 4: is the VAT on the cash payments you have made (not invoices received)
Box 6: total cash sales (£1,000)
Box 7: total cash purchases ( £200)