Disallowed expenses can be easily identified and retrieved in Odoo from V14 thanks to the module ‘Disallowed Expenses’. This module is either automatically available or can be downloaded from the database (in Apps). 

To do so, configure the disallowed expense category appropriately (Accounting > Configuration > Disallowed Expenses Categories) as follows :

Define the non-deductible rate and start date for the disallowed expense category and the associated account(s) from the CoA (i.e. 610010 Car expenses). The counterpart is visible on the account itself as follows (Accounting > Configuration > Chart of Account) : 

When booking a bill, the correct expense account must be set.

By using the account linked with the disallowed expense set previously, the expense is now registered and visible in the ‘Disallowed Expenses Report’ (Accounting > Reporting). The total disallowed amount can be displayed for a certain period, for all or specific journals, and can be retrieved in PDF or Excel format.

Note: If you are using Fleet application, the expense can be directly associated with one of the vehicles by adding its reference on the bill line.