Last summer, when Britons voted to leave the European Union, many wondered if the Crown would actually follow through, invoke Article 50 of the Lisbon Treaty, and file paperwork to make it official.

Today, however, after Prime Minister Theresa May gave the EU formal notice of the UK’s intent to leave, it’s clear: Brexit is a lot closer to happening, and Brits likely will go out on their own by no later than March 2019.

Depending on the ability of both sides to negotiate extensions of existing relationships, the divorce could have a far-reaching impact on everything from trade to transporting pig semen (seriously; CNN put together a great story about 50 things the UK needs to do after triggering Article 50).

One of the specific areas that’s likely to change quite a bit: travel, especially within Europe. 

We first wrote about the potential impacts of Brexit in June of last year. The latest step on the road to a separate United Kingdom has us thinking about some of the issues yet again.

No. 1 on the list is customs. Right now, EU rules allow Brits to live and work in any of the 28 member countries and allow residents of EU countries to live and work in the United Kingdom. Similar rules also allow free movement across borders to other EU nations. By leaving the EU, Britain could jeopardize both of these arrangements, creating a situation where U.K. citizens need visas to visit (or live and work in) other European nations, and EU citizens need visas to visit the United Kingdom.

The situation could get particularly dicey within the United Kingdom itself. Ireland is a member of the EU and is planning to stay so, but Northern Ireland happily is part of the United Kingdom. Without some sort of new agreement or arrangement governing travel between the two, it is conceivable that U.K. citizens would need passports to travel from Belfast to Dublin. 

(In related news, if Scots vote to leave the United Kingdom and join the EU, then without some sort of special provision, English citizens would need passports to see footy matches in Edinburgh.) 

Air travel between the United Kingdom and other EU nations also could be impacted. According to various news articles, flights to and from the United Kingdom are covered by an Open Skies agreement with the EU, and airlines need a new agreement in place by summer 2018 so they can plan their flight schedules for 2019. 

The price of airline tickets also could change, since budget airlines such as U.K.-based EasyJet would have to renegotiate contracts to operate in EU airspace.

The situation might even affect air travel passenger rights. A story on CNN indicated that EU citizens are entitled to certain forms of compensation if their flights are delayed or canceled (or if they’re booted from the flight against their will). If the United Kingdom formally leaves the EU, then without some type of agreement, U.K. citizens no longer would be eligible for these benefits. 

Unfortunately, we don’t have many answers to these questions right now; the future depends on which EU laws Brits decide to keep, how May’s government decides to repeal current arrangements with EU nations, and how successful the United Kingdom is in ironing out new agreements.

These efforts should play out over the coming year. For the sake of travelers everywhere, let’s hope the transition goes smoothly.

 Matt Villano is a freelance writer and editor based in Healdsburg, California. In nearly 20 years as a full-time freelancer, he has covered travel for publications including TIME, the Wall Street Journal, the New York Times, Sunset, Backpacker, Entrepreneur, and more. He contributes to the Expedia Viewfinder blog and writes a monthly food column for Islands magazine. Villano also serves on the board of the Family Travel Association and blogs about family travel at Wandering Pod. Learn more about him at Whalehead.com.

>>Next: Emirates Unveils Genius New Service