Tax code box on Bank Receipt page

I cannot see what the Tax code box does on the Bank Receipt page. When recording a payment, whether this box is left blank or (in my case) I select 15% VAT - all reports appear to be identical.

If the payment being receipted is linked to the invoice in question - and that invoice includes VAT then why doesn’t the Tax Code box default to the same as the invoice?

PS. I’m a business owner/user not an accountant or bookkeeper.

The Tax code on the Receive Money transaction is used to keep track of VAT when you record a sale without an invoice - ie a cash sale

If you are recording the receipt of money for a credit sale ie with an invoice, then the VAT information will be on the invoice and should not be entered on the receipt.

Your Tax/VAT reports can be on accrual or cash basis and will adjust VAT accounts accordingly