We all know that having a passport is the main requirement for an international trip, and many of us are aware that you need at least six months of validity on that passport for many destinations (if you didn’t, here’s your warning!). But did you know that your passport must also be in fairly good condition? Damage can actually invalidate your passport, putting an early end to your long-awaited vacation. So to avoid any issues on your next international trip, here’s everything you need to know about passport damage.

Types of Passport Damage

There are two main types of passport damage — normal wear and tear and genuine damage — but the line between them can be blurred, and the final judgment call comes down to the individual examining your passport, whether that’s an airline employee or an immigration officer.

“Wear and tear is okay most of the time,” says William Lee, a travel agent at Chima Travel. “However, any sort of damage to the passport does introduce the possibility that an airline or country refuses entry.”

Here’s what you should know about the two main types of damage.

Normal Wear and Tear

The U.S. Department of State says that “normal ‘wear and tear’ such as folded pages or a small bend do not count as damage.” Of course, it’s not only the U.S. Department of State that’s examining your passport. Immigration officers in other countries might be stricter with their definition of “normal wear and tear,” but generally speaking, slight fading, fraying, or bending shouldn’t be an issue. If you aren’t sure if your passport damage is considered normal wear and tear, play it safe and get a new one.

Damage

The State Department considers significant damage to be “stains from a liquid, a significant tear, unofficial markings on the data page, missing visa pages (torn out), or a hole punch.” Typically it’s the data page — the one with your photo — that’s the most important. But any significant damage anywhere in your passport could pose a problem.

A side note: Novelty passport stamps, such as the ones you can get at Machu Picchu in Peru or Port Lockroy in Antarctica, can also be considered “damage” and thus render your passport invalid. If you look at page five of a U.S. passport, it notes that “only authorized officials of the United States or of foreign countries may place stamps or make notations or additions to this passport.” While not all airline or immigration officials will ding you for a novelty stamp, it simply isn’t worth the risk. So instead of stamping your passport with a novelty stamp, stamp a separate piece of paper or page of a small notebook instead.

“A ‘damaged’ passport can mean a lot of things, but in truth, it can be difficult to travel with even small damage on your passport,” says Lee. “It’s imperative that the passport photo and data page are okay. If those elements of the passport are damaged, then the passport will not be usable for travel,” says Lee.

Since there’s no hard-and-fast rule that’s followed worldwide, it’s better to replace your passport with slight damage before your trip. No one wants to fly halfway around the globe just to be sent back home due to a damaged passport.

Traveling With a Damaged Passport

If you travel with a damaged passport, your fate is in the hands of the official examining your passport. “Technically, you can travel with a passport that has minor damage, but it’s risky. Airlines and immigration officials may deny boarding or entry if they consider the damage significant,” says Duncan Greenfield-Turk, chief travel designer of Global Travel Moments, an affiliate of Global Travel Collection. Again, it’s always better to replace a damaged passport before your trip.

What to Do If Your Passport Is Damaged

If your passport is damaged before a trip, it’s best to replace it as soon as possible. While many U.S. passports can be renewed online these days, damaged passports are ineligible for this service. In fact, you can’t even renew your passport by mail if it’s damaged. Instead, you’ll have to apply for an entirely new passport. Per the State Department, you’ll have to submit the damaged passport, a “signed statement explaining the damaged or mutilated condition of your passport book and/or card,” and Form DS-11.

Note that if your valid passport has been damaged (or lost) due to a major disaster, the State Department may waive all fees associated with replacing it. But if your passport was expired at the time of the disaster, you’ll still have to pay the fees. You can see a list of eligible disasters on the State Department website. In terms of the process, you’ll have to fill out and submit Form DS-5504 (Replacement Passport Form) and Form DS-64 (Lost and Stolen Passport Form).

Now, if you’re abroad when the damage occurs, your situation is quite different. “If your passport is damaged abroad, head to the nearest embassy or consulate to apply for an emergency passport. This will allow you to return home but may not grant access to other countries,” says Greenfield-Turk.

How to Prevent Passport Damage

Store your passport wisely, both at home and while you’re traveling. “Luckily there are many passport protectors out there. Amazon has a ton to choose from,” says Lee. “Outside of that, best practice is to store the passport in a place where it can’t get water damage, ripped, torn, or bent.”