Cho Seong Joon / via Frommers.com

The lobby of the Grand InterContinental Hotel in Seoul, South Korea.

Most hotel websites offer a "price guarantee" — a reassurance (backed by a price match, additional discounts, credits, free nights, or other promises) that you won't find a lower room rate for a similar category room elsewhere.

The potential perks should be enough to ease the mind of anyone who's thinking twice about making a reservation, right?

Sure, at least that's what hotels want you to think. But hone in on any rate guarantee to see how to cash in, and you'll be squinting at so much fine print (much of it legalese) that you may need a pair of reading glasses.

Read More: Find the best ways to book hotel rooms

When it comes to deciphering price guarantees, here is what to watch out for when reading through the requirements, and what to do if you find a lower price.

What do price guarantees cover?
So you've clicked on "book" to confirm your reservation on a hotel website — only to find a room that's priced lower on another site! Now what? Do you qualify for a price match, credit, or additional discount under the hotel's promise of the best rate? Though price guarantees vary slightly from brand to brand, here are five eligibility requirements that you can expect across the board:

1. The room that you found on a different site must be exactly equal to the one that you booked. This means that everything — including the bed size, the views, the dates of the stay, number of guests, and the cancellation policy (did you book a prepaid, nonrefundable rate?) — must be comparable to the room that you booked on the hotel website. The price must also be quoted in U.S. dollars (as foreign exchange fluctuation can often account for rate differences.)

2. Negotiated, promotional, or group rates don't count; neither do those found on opaque, auction, and membership (including flash-sale) sites. You can't compare the price of the room that you booked with a room bought with an AAA, AARP or other membership discount. You also can't compare room rates with prices posted on sites like Hotwire, Priceline, Jetsetter, SniqueAway  and Vacationist.

3. You'll need to file a claim within 24 hours after you book. The actual amount of time that you have to take advantage of a price guarantee is limited — usually 24 hours, though sometimes up to 72 — so you'll need to act fast (or even better, think before you buy).

4. The deal must be bookable at the time your case is reviewed. The sooner that your case is reviewed, the better — or else the link with the competing price may expire.

5. Guarantees are calculated on the base fare. So be sure to subtract taxes, booking fees, or other charges when comparing your reservation and the website that's offering a better deal.

If these five conditions alone seem limiting, it's because hotels know exactly what they're doing. Hotel rates — similar to airline pricing — change quite frequently, even hourly. But it's uncommon for a dramatic price decrease to occur within 24 hours of booking (and even more uncommon for a traveler to take the effort to search for it). Hotel guarantee claims typically need to be filed within 24 hours after you book, but statistics reveal that price drops are more likely to occur over a longer period of time. Out of the 200,000 hotel stays registered through hotel (and airfare) price-tracking site Yapta.com, 31 percent experienced a rate drop. Out of that percentage, only 19.56 percent happened over a period of 0-6 days; the average rate drop occurred over a period of 36 days — long after the window for filing a claim has expired.

How to file a claim for hotel guarantees
Despite the odds, chances are that you may find a more attractive room rate on a competing site. Luckily, the process of filing a claim is straightforward: most hotel groups will recommend that you call their reservations line or direct you to an online claim form. You'll have to provide your booking confirmation number, and the URL that links to the better deal. In some cases, your claim can be resolved quickly — and when price matches are offered, at least in time for your stay.

If you can't be bothered with a claim, then it's possible to cancel and rebook at the better price (assuming that your purchase was refundable, and that you won't be paying a penalty; check your hotel's cancellation policy).

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