Based on customer feedback, in Sage 50 Accounts Professional v28.1 and above we've introduced the option to flag a supplier invoice as disputed at the point you post it. It's quick and easy to do, whether you're posting a batch invoice or updating a purchase order.  

Add a disputed flag when you post a batch invoice

1. Click Suppliers then click Batch invoice.
2. Enter the invoice details as normal.
3. For each disputed row, in the Disputed? column, click the drop-down and choose the dispute reason.
4. Click Save then click Close.

That's it. The supplier invoice is posted with a disputed flag and you can view it within the Disputes area.

Add a disputed flag when you update a purchase order

1. Click Purchase orders, then click the order you want to update to the ledgers.
2. Click Update ledgers then click Update.
3. For each disputed row, in the Disputed? column, click the drop-down and choose the dispute reason.
4. Click Save.

That's it. The supplier invoice is posted with a disputed flag and you can view it within the Disputes area.