....(I think I should have about 4 BNB left but Binance says that I have about 9). Is there a possible explanation for this other than me being a muppet?
Maybe it's just the difference in timing of the report. Compare the dates you downloaded the report or its cut-off date to the time you had your last transaction.
Example,
June 30, 2022 - your balance was still 9 BNB.
July 1, 2022 - you sold 5 BNB
The coverage date of your tax report is until June 30 only.
I'm guessing the above sample is what happened in your case that's why you think it should only show 4 BNB.
Thanks for your response.
The dates I'm interested in are the tax year 21/22 which happen to start/end in April where I am (not sure if this is universal).
1) I had zero BNB at the start of that tax year (April 2021)
2) At the end of that tax year (April 22) my transaction history (only seven transactions directly involving BNB [excluding BNB fees]), read that I should have about 3.5 BNB left (less if you consider the BNB fees).
There's a disconnect on the 3.5 balance by April and then selling 4.5 in May but I'm still going to focus on the cut-off dates. Can you confirm if your taxable period starts on April 1, 2021? It should end on March 31, 2022 if that's the case. Reconcile the tax report with the transactiom history again but up to that period only.