If you do end up with a statement loaded with the incorrect VAT rate, then you can easily correct it in one of 2 ways:
Method 1
Update the VAT percentage in the existing statement record as loaded on Commspace, found under More Options.
This will trigger an automatic "re-processing" of the statement i.e. recreating the statement record from the source statement file (typically Excel/CSV), this time using the update VAT percentage.
Method 2
Simply reimport the commission statement, this time setting the VAT percentage to the correct value before uploading.
Note: in some cases we read the commission statement's line item VAT value directly from the statement file during uploading, so changing the statement VAT percentage will not result in different statement item VAT values in this case.