As we calculate your trading, we build up a running total of your assets, each with its own cost basis. Each time one is disposed (sold or traded away) they are removed from that balance. If the balance goes negative, where you are effectively selling something you don't own, you will see the "more sales than purchases" or "unmatched trades" error:

At this point your data is not accurate since we have not been able to calculate from all the original values. The message is to let you know that the data needs to be corrected and the resulting gains and balances are likely inaccurate, since we have had to make assumptions about the missing coins.

This can happen if:

• You have not included all your trading activity
• You have not included all your digital currency income for the year
• Your have not added the coins you owned before the start of the year to the Opening Tab
• You have incorrectly uploaded your data

Please make sure you have included all your trading, sources of income, and other activity for the year. Some of the more common causes of unmatched trades can be found in this section. 

You can view your unmatched trades by going to the Reports & Export Tab and then selecting -> Options -> View Only Unmatched. The unmatched trades will be highlighted in red, as seen below:

If you are not sure what is causing these unmatched trades, please reach out to our support team at support@bitcoin.tax - our team is always happy to assist.