Can I show my customer the local city tax they have to pay at the hotel so they are not surprised at check in?

Yes, in most cases you can, because many hotel suppliers pass the city tax or resort fee through the API as a separate charge that is marked payable at the property rather than as part of the amount you collect. When that information comes through, your portal can display it on the room result, on the quote and on the voucher, so the guest knows there is a small amount to settle at reception.

The usual way to handle it is to keep it outside your own total. You collect the room rate and your markup through your website, and the tax line sits underneath as a note saying it is paid directly at the hotel. Some suppliers send it in the local currency of the city, so it may not convert neatly into the currency your customer is shopping in, and it is safer to show it as the supplier states it rather than guess a conversion.

Being honest about the limits, this depends on the supplier and on the property. Not every supplier returns the tax as its own field. Some include it in the rate already, some write it only in the rate description text, and some leave it out completely for certain cities. Taxes can also vary by the age of the guest or the length of stay, so what you show may be an estimate rather than an exact figure. The best you can do is display whatever the supplier gives you and word it as payable at the hotel.

A good next step is to run a few searches in test mode for cities you know charge a tourist tax and see what your suppliers return, then tell us which fields you want printed on the voucher and confirmation email.