In Thai Restaurants
When visiting a restaurant together it is custom that the party having the highest social status takes care on the bill for all attendees or instructs someone else to do. It is also quite common that you are asked for your income if the Thais cannot judge on your status. As in normal case we have a higher income – what in turn presumes a good Karma - nobody will have a problem with the Farang taking care on the bill ...
Also is generosity generally welcome so that "jumping the queue” is loved to be seen when it is about to pay. When you are inviting for a meal it is likely to happen that the invited person brings somebody along with without giving notice. But as in Thailand is taken from all dishes and pans standing on the table this is irrelevant. In case an invited person doesn’t show up it is often due to the fact that the embarrassing situation of a cancellation is avoided by this.
A tip is usually not given only outstanding service can be honoured with an additional amount (max. 5 % of the amount invoiced).