The taxes calculated and shown on the Invoices are controlled by the Tax settings in your Shopify admin. Shopify doesn't automate retroactive tax calculations, so if you just finished adding your taxes, there’s no way to adjust taxes for all past orders.
There are situations in which making a tax correction is necessary; however, since tax filing and remitting require direct registration with your local or federal tax authorities, you must consult a tax professional before you make any changes.
Recommended solution
You may go through your past orders to identify which ones require adjustment and, depending on the tax rules for your specific jurisdiction, calculate the correct amount of tax that should have been collected at the time of each sale.
Then, to issue updated invoices to your customers, you must do the following:
Make sure you've adjusted the proper tax on your Tax settings
Duplicate the original order and make sure the taxes are applied
Print the new order with Order Printer Pro
Cancel the original order
If you need help with this process, we recommend contacting Shopify for complete guidance.
On the other hand, if you need to edit many orders or make constant adjustments to them, we recommend checking order editing apps like the Edit Order app by Cleverific. This app allows for easy Tax Adjustments, among other types of edits.
If you use an external service for tax submission to the authorities and your accountant recommends making a manual correction to the invoice, you can contact our support team, and we'll do our best to help.