I just recently went through an audit.  I keep the invoices both digitally and a hard copy.  The issue was matching the Tax Exemption & Capital improvement Certificates with the invoices.   And then making sure they were not expired.  I looked through Zoho products and could not find a solution or a way to do this in the CRM.  Maybe I just can't find it.   When I look outside Zoho I found this  https://sovos.com/products/tax-determination/certmanager/.  However I am not looking to use another platform, as I already use Quickbooks, as per my accountant,  and Zoho.

I think this is an idea with exploring, because every business may have to go through an audit, and having accurate records is a time and money saver.