Even frequent travelers scratch their heads when it comes to how much they should tip hotel employees, tour guides and others who provide services when they are on the road. The holiday season, however, adds another element of confusion to a practice that is already perplexing enough: Are you supposed to give an extra tip in the spirit of the season to the concierge at your hotel who helps with dinner reservations or the Uber driver taking you to the airport? What about the travel agent you use to book your vacations?

Here, travel industry experts share their advice on who and how much to tip over the holidays:

The season, generally, warrants extra tipping. Reneta McCarthy, a senior lecturer at the School of Hotel Administration at Cornell University, who has lectured on tipping in the hospitality industry, says that from Dec. 15 through Jan. 1, tipping at least 25 percent above the usual tip amount to anyone who serves you when you’re traveling is a much appreciated gesture. People to consider include the van driver of the free airport shuttle who takes you to your hotel and helps you with your bags, the Uber or Lyft driver who gets you to the airport through heavy traffic and hotel employees such as bellhops, housekeeping staff and servers. “Remember that these people are working hard through a very hectic season, and it’s nice for you to show them that you recognize this,” Ms. McCarthy said.

Frequent hotel guests should tip double. If you’re a regular at a certain hotel and staying at that property over the holidays, it’s a good idea to tip twice what you normally would, according to Josh Alexander, a travel specialist at Protravel International, based in New York, who has written tipping guidelines for his clients. “Regular hotel guests often receive exceptional service, and the holidays are a time to reward that service,” he said.

Baseline tip amounts at a luxury hotel, he said, are $5 a day for housekeeping, $3 to $5 per bag for bellhops and $2 to $3 for employees who call you a taxi or hold the door open for you. Concierge tips vary from $5 to $50, depending on how elaborate your request is.