At a Czech restaurant or pub, a tip is a voluntary thank-you rather than an automatic American-style surcharge. The most useful custom is procedural: when the server tells you the bill, say the total you want charged, including any rounded-up tip. The number becomes the end of the payment.
Turn one bill into one spoken total
A percentage is a guide, not a command
Say it before the terminal confirms
If you pay by card, state the desired total while the server is preparing the terminal. Check the displayed CZK amount before tapping. A tip prompt can be declined, and a server should not select a percentage or add an amount without your agreement.
Cash uses the same sentence
Handing over a large note and saying the final total tells the server how much change to return. If the bill is 468 Kč, giving 1,000 Kč and saying 500 means you expect 500 Kč back. Saying 'thank you' too early can sometimes be understood as 'keep the change,' so lead with the number.
Read before adding
An unusual venue, hotel restaurant or large group may disclose a service charge. It is part of the bill when clearly included and should be understood before another gratuity is added. Ask when the receipt is unclear rather than paying the same thank-you twice.
Taxis need a correct fare first
For a metered taxi or app ride, check the route and displayed total. Rounding a fair fare for helpful service is optional. A gratuity never repairs an unclear meter, an unofficial price or an unwanted home-currency conversion.