Of course, anyone who regularly travels for business or works in the travel department of a company knows how much the airline carriers look for clever ways to jack up prices. Hotels are no different, and they are earning a staggering amount of money doing so.

According to an annual trend analysis report by Bjorn Hanson, a professor in hospitality and tourism at New York University’s School of Professional Studies, hotels in the United States took in a whopping $2.55 billion in fees and surcharges in 2016. That’s a 4 percent increase from the year before.

From early check-in to late checkout and even the coffee you prepare yourself in the room, hotels increasingly are finding ways to charge for amenities that previously were provided for free. And as properties are becoming better at disclosing the extra fees and hotel employees are being trained how to politely handle complaints, it’s getting harder for guests to get these add-on charges waived when checking out — which is why business travelers and travel managers alike need to pay extra-close attention to the fine print before reservations are made.

To help in the meantime, here are eight hidden fees to be on the lookout for and how you may be able to work around them.

1. Early check-in/late checkout

Business travelers who have places to be (preferably without being tethered to their luggage) need flexibility when it comes to checking in and out of their hotels. Unfortunately, hotels increasingly are charging guests for checking in early or out late, sometimes up to $50 per request. But you may be able to avoid all that by joining a hotel loyalty rewards program that offers early check-in/late checkout as a perk. For instance, Starwood™ offers its rewards members a late checkout of 4 p.m., subject to availability.

2. Wi-Fi

Despite how many places provide free Internet access to the public, it seems hotels are getting stingier in this department. These days, you can expect to pay a daily fee of up to US$20 for the privilege of using a hotel’s Wi-Fi service. Some hotels actually charge per minute of usage instead of a flat daily fee. And for those bringing along a traveling companion, beware of properties that charge per device, not room.

One way you can avoid paying for Wi-Fi? Join American Express Global Business Travel (GBT)’s PREFERRED EXTRAS™ program, which offers members free additional perks like Wi-Fi and/or breakfast at 45,000 properties in nearly 180 countries. Alternatively, you also can use your smartphone as a hot spot — but then just be sure you’re not racking up enormous roaming fees.

3. Parking

Business travelers cruising up in a rental car or in their own set of wheels likely will be slapped with a hefty parking fee and have to tip for the mandatory valet service. In larger cities, expect to pay US$40 or more to keep your car parked in their lot or garage. If that’s the case, look into nearby garages for a lower rate. Or really save by ditching the car altogether and take a taxi or shuttle service. Who wants the hassle of navigating your way around a foreign city anyhow?

4. Room service

The price for in-room dining can be huge. It may not be that the menu prices necessarily are any higher than what you’d see in the hotel’s restaurant, but there often are add-ons, such as a “tray delivery” surcharge as well as an 18 to 20 percent gratuity already built in. So be sure to read the fine print when the attendant asks you to sign the bill, which will quickly make you realize how much more expensive it is to have a meal when picking up the phone rather than picking up yourself. To avoid that, just take a trip down to the restaurant, order your food, hang in the lobby with your laptop until it’s ready and then head on back for an in-room dining experience without a side dish of buyer’s remorse.

5. Beverages

Many hotels offer a couple bottles of water, coffee and tea. But nowadays you can’t be so certain those “complimentary” items are indeed free. Some bottles of H20 and K-cups may cost more than what you would pay at a Starbucks™. So be sure to read the labels carefully before gulping anything down. If in doubt, put in a call down to the front desk first. And to avoid getting caught paying US$5 or more for water, bring along a bottle with a purifying system and fill up at the sink.

6. The minibar

If you don’t want to rack up a sizeable minibar tab, you can look but don’t touch. Even if you don’t consume any of the goodies inside, just by jostling a bag or bottle in the miniature fridge may set off a sensor and the price of that item automatically will be added to your bill. Even if you do decide to pay 10 times the amount for that can of nuts, realize you may incur an additional “restocking” fee for the staff to replace any items you took. So what’s your best defense? Bring your own stash of snacks to quell any hunger pangs.

7. Housekeeping

Some hotels now charge for that most basic of guest expectations — maid service. A “housekeeping fee” or “housekeeping gratuity” may be automatically added to your tab. If you see this kind of fee on that bill slipped under the door, inquire about it when you check out. You actually may be able to get this one waived. If not, be sure you do not leave a tip for the maid on the table when vacating the room.

8. A different rate than you’ve bargained for

Finally, this last nugget of advice is for travel managers. Now, you might expect after all the back-and-forth negotiations with your preferred suppliers that your travelers simply would get the rate you’ve worked so hard to obtain. After all, the hotel properties fully expect you to meet your end of the bargain by ensuring a steady stream of your people entering through their doors. But you may be surprised to learn how often they fall short. That’s because preferred rates aren’t always properly loaded into the distribution system.

Often corporate rates aren’t loaded during the first round of audits typically executed shortly after program implementation. It’s also common for hotel properties to limit the number of rooms eligible for the special rate. Translation: You may not be getting your negotiated discount, especially when the hotel is nearly or fully booked.

How can you avoid such a situation? Conduct an audit with your preferred vendors to see if you are indeed getting the rate you have negotiated for. If you find you’re not, it may be time to say you’re taking your business elsewhere — if they don’t agree to waive all the other above-mentioned fees.