[Quoth]

Kobo wants a country on the payment method. If the country has regional tax variations then you'll need at least the area/zip. UK and Ireland only need the country.

Also your payment method needs to be compatible. Paypal used to work for me for USA, but last time it didn't, but my Irish Current Account (bank HQ in Lithuania) sort of worked. I had to manually unfreeze the automatically frozen account and approve payment in the App, but it worked. Paypal is working OK for UK & Ireland.

Kobo only geolocates via IP to suggest which store if you are not logged in. If you are logged in, then the country (only if entire country is same rate or even no tax) or address (if regional taxes in the chosen country) overides the IP address.