Hello @jzhu
In Acumatica, Tax IDs will be added to the document based on the tax category and the tax zone.
The users can manually change the taxable amount and tax amount on the Taxes tab. And also users can remove the Tax IDs manually. Before releasing the document they can re-add those Tax IDs (if needed).
However, users cannot add Tax IDs that do not match with the tax category in the details tab and the tax zone on the document.
In addition, my recommendation is that if users manually adjust tax details in the documents, you can enable the field-level audit. If we enable the field-level audit we can know what modifications are done by users.
Hope this helps!
Thank you.