Right, I've got it wrong on the specific example, but not on the whole concepts.
And still, the question remains as to which items Chris has bought and sold. ''My sales for the year were £189, and my purchases £281.'' doesn't say anything in relation to whether or not there has been profit.
If I buy items A and B for £ 100 each and sell item C for £ 200, it doesn't necessarily mean there has NOT been any profit. I could have bought item C for £ 20, thus there would have been profit for that item. The DWP or HMRC would want details, not generalities. Just saying.
