Have they cleared the tax data?

no. they have not as they are going to file the tax return.

Not even by accident?

Is this the first time they have done tax reporting or has the system been used before?

They are using it. they last file the tax upto December 2019. 

OK, so the system is set up correctly.  The only way I know for the tax tracking tables to be cleared is by running Tax Periodic Processing > Clear History.  Are you certain this wasn't done?

I have Asked them the same. They are saying they have done it. but can be possible if someone did it. not sure. any way to update the tax tables again from AR & AP Tables?

It might be possible with SQL but very difficult.

I don't know of any way through Sage 300 or using any utility.

ok.. thanks. one quick question regarding inventory Serial Number stock On Hand Report. there is a variance in Serial on hand and No of Serial and having variance. what is the possible reason that they are not matching?  Serial On hand and Qty on Hand are matching only in the IC serial/qty on hand report is having a variance

Not sure without looking at the data in question.