You need to setup one of the following to load purchase taxes automatically:
- A Purchase Taxes and Charges Template with Tax Category configured. Additionally, tax category can be set in the relevant Supplier or Address for accurate fetching.
- A default Purchase Taxes and Charges Template for the relevant Company.
- A Tax Rule based on which a tax template gets set.
You can read more about Tax Rules, Tax Templates and Tax Categories in the documentation:
https://docs.erpnext.com/docs/v13/user/manual/en/introduction
We are working on improving this flow so that taxes can be automatically added without requiring configuration of Tax Category. You can track it here:
https://github.com/resilient-tech/india-compliance/pull/223