VAT CALCULATION BASED ON VAT NUMBER

The EU VAT Assistant has no effect on the VAT calculation. The calculation is handled entirely by WooCommerce, this plugin only collects the data after the calculation is complete.

WooCommerce only calculates the VAT based on the country, therefore you will have to implement some custom code to add your own calculations. One solution could be to create a second VAT rate class, setting custom percentages, and assign the appropriate class if the customer entered a valid VAT rate. To get started, you could use the sample code from the article showing how to change the tax class depending on customer’s role, and the wc_aelia_eu_vat_assistant_customer_vat_exemption filter to check if the customer entered a valid VAT rate.