How can I change GST input tax from 0% to 10%?

Hi david-marnell,

You can change the GST input tax manually on a transaction. Kindly open the transaction and on the GST column select the correct tax code applicable on the transaction and then select Save. You can also select on the Amounts are drop-down menu if it is Inclusive of tax or Exclusive of tax. 

If you would like to change the GST codes of your transactions in bulk, you can contact your accountant as they have an option to reclassify your transactions. For your reference, you can also check on this article: Bulk reclassify GST Codes on transactions. 

Feel free to drop a comment below if you need further assistance. Have a nice day!