Hi,
If you are using the auctioneers margin scheme then as per the guidance below:
You should:
Work out the purchase price and selling price
Take away the purchase price from the selling price to work out the gross margin
Multiply the gross margin by 1/6
The VAT due is the difference between what you paid for the goods and what you sold them for, not the overall profit you have made on them.
As you are an agent acting in your own name for these transactions then your taxable supplies will be the selling price of the goods.
Therefore when considering your taxable turnover you would need to use your selling price and not the margin.
Please see the guidance below:
Using the auctioneers' VAT margin scheme How the scheme works
VAT guide (VAT Notice 700) 22. Supplies made by or through agents
Thank you