Which exporting rules are mandatory to sync a transaction with Dynamics 365?

To be exported to Dynamics 365, each transaction must be tagged with an item from the ‘Expense Category’ list.

You can also make it mandatory for each transaction to include an attachment if you wish. This can be done either during the setup flow in the final ‘Transaction rules’ step, or once the integration has been set up. To change the exporting rules once the integration has been set up, find the active Dynamics 365 card in the ‘Marketplace’ section, click on ‘Settings’ and choose ‘Transaction rules’ from the tabs at the top of the page.