Tax Reversal gives you the sum of the tax amount applied all over the voided invoices (Voided at date filter applied) and the tax applied over the credit notes.
For example, consider the below account summary details:
For the month of December-2019, Tax reversals are mentioned as $288.49 in the Account summary report. This amount includes a collection of, credit notes and voided invoices.
Credit Notes: The image attached below is a filtered result of the credit notes that were generated specifically for the month of December 2019. (Filter applied: Date). The total amount is $151.46. as specified.
Voided Invoices: The image attached below is a list of invoices voided in the month of December 2019, the total amount is $137.02. (Filter applied: Voided At Date)
The total amount of $288.49 can be obtained by summing up (a) and (b) as mentioned in the account summary report.
Where can I see the details for Bad debt
Account Summary Report abstract