Sometimes you can see different tax amounts in your Tax and Z/X report or Product Mix report for a certain period of time.
This is an expected system behavior. Tax calculation rule in Z report is the following:
if there was a refunded transaction of previous batch, Z report deducts tax amount of returned transaction form current batch instead of original one.
At the same time, Tax report for a particular day doesn't include refunded transactions for previous days.
For example:
During current shift 2 items were sold using current register, and tax collected was $3. Tax report will show this $3 amount, the same as Product Mix Report.
During the same shift, 2 items for a previous day were refunded, and then current POS register was closed.
Tax report and Product Mix report will be the same, they will show the amount of $3, but Z report will be different in terms of tax amount, as it includes refunded tax (-$2).
So tax amount in Z report is equal to actual tax amount minus refunded tax: $3 - $2 = $1.
At the same time Tax report for the day the refunded transactions were run will show the actual tax amount:
[actual tax] = [tax collected] - [tax refunded].
When paying taxes, please run Tax reports as they contain the most precise information.