IR Investigation

Self employed trader in mainly cash business hasn't kept records of cash in & out of the business separate from personal cash. The revenue contend that by assuming drawings were taken out the business at the same level each week (not correct) this would result in negative amounts therefore more money must have been received. If the cash flow was reworked to show more realistic seasonal drawings then the negative balances would disappear.

The traders problem is that he didn't keep records or count cash at any time as he thought that keeping copies of all sales/purchase invoices and keeping records of cash sales would be sufficient.

The revenue can't prove that undisclosed sales took place but neither can the trader prove they didn't.

What is not in dispute is the fact that insufficent records regarding cash reconciliations were kept or that personal & busines money were kept separate.

The revenue suggested a negotiated settlement.

Is this worth taking to appeal & what would be the chances of winning? - I know, how long is a piece of string but if anyone has any experience of this sort of investigation comments would be appriciated.
Julia