How do I select a tax code when adding a transacton to qb online? nothing is appearing in the drop down box and I can't free type anything into it.

Hello Tonyf1, 

Welcome to the Community page, 

It shoulds like the vat code are not turned on that is why you are not seeing them select one. 

If you go to the taxes tab left-hand side of Quickbooks> on the vat page-top right-hand corner edit vat>edit rate>make sure all the ones you need are toggled on green> this they are toggled on then if you go back to your transaction you'll be able to select the code you need to use.