Visa rules are dull, they change frequently, and they are enforced by people with no discretion and no interest in your itinerary. Almost every visa problem a traveller has is one of five things, and all five are avoidable with an hour of preparation.
Nothing here is a substitute for checking the current requirement for your passport and the specific entry point, on the country’s own government site.
The five things that go wrong
1. Passport validity. Most countries require six months’ validity beyond your date of entry, and some require it beyond your date of exit. Airlines check this at the departure gate and will refuse boarding.
2. Blank pages. Several countries require one, two or even four completely blank pages. Pages with stamps do not count. This is the one that catches long-term travellers, and adding pages is no longer possible in most countries — you need a new passport.
3. Onward or return ticket. Many countries require proof, and airlines enforce it whether or not immigration would. A one-way ticket into Southeast Asia, Central America or the Caribbean is where this bites.
4. Applying from the wrong place. Some visas can only be applied for from your country of residence. If you are already travelling, you cannot get one, and finding this out in month four of a trip is a real problem.
5. Miscounting a rolling window. Overstaying is treated as an immigration offence, not an administrative slip, and it can produce a ban.
The types, briefly
Visa-free. Nothing required beyond a passport, usually for a set number of days.
Travel authorisation — ESTA for the US, eTA for Canada, ETIAS for Europe, K-ETA for Korea, and the UK’s ETA. Not visas, applied for online, cheap, and required before boarding. Apply days rather than hours ahead; most are instant and some are not.
E-visa. Applied for online, approved in days, printed or held on a phone. India, Turkey, Vietnam, Kenya, Sri Lanka, Egypt and a long list of others.
Visa on arrival. Obtained at the border, usually for cash in a specific currency. Crucially, it may be available at airports and not at land crossings — see the border guide.
Embassy visa. An application in person or by post, weeks in advance, sometimes with an interview. Increasingly rare and still required for some countries.
The Schengen rule, which trips up more people than any other
Most non-EU visitors get 90 days in any rolling 180-day period across the entire Schengen Area, which counts as one country for this purpose. Leaving France for Spain resets nothing.
It is a rolling window: on any given day, count how many of the previous 180 days you spent inside the area. Use one of the official calculators; the arithmetic is genuinely counter-intuitive.
Outside Schengen and therefore useful for resetting: Ireland, the UK, the Balkans outside the EU members, Turkey, Georgia, Morocco.
The EU’s EES biometric entry-exit system removes any ambiguity about the counting, and ETIAS adds a pre-travel authorisation. Both have been phased in on repeatedly shifting dates; check what applies close to travel.
Similar traps elsewhere
CA-4 — Guatemala, El Salvador, Honduras and Nicaragua share one 90-day allowance between them. Moving from one to another does not reset it.
The Gulf states, Southeast Asia and much of Africa have their own bilateral variations that depend heavily on nationality.
Some countries count a day of arrival and a day of departure as two full days. Read the wording.
The politics that affect entry
Israeli stamps historically barred entry to several countries. Most now issue electronic entry records rather than stamping, but underlying restrictions remain in some states.
Nagorno-Karabakh evidence bars entry to Azerbaijan.
Entering a disputed territory from the “wrong” side — Kosovo from a third country before Serbia, Abkhazia from Russia before Georgia, Northern Cyprus before the Republic — can result in refusal.
If your route touches any of these, check the sequence, not just the countries.
Practical process
Build a spreadsheet before booking anything: country, your passport’s requirement, cost, how far in advance, whether it can be obtained on the road, and validity from date of issue or date of entry — which are different and matter.
Apply through official government sites only. There is an entire industry of intermediary sites that charge several times the real fee for filling in the same form.
Print everything. A phone with no battery at a land border is a bad place to be storing an approval.
Photocopy your passport and keep copies offline and in cloud storage, plus two spare passport photographs, which are needed at land borders constantly.
Check the validity clock. Many e-visas are valid for entry within 30 or 90 days of issue, not from your arrival date. Applying too early is as much of a problem as applying too late.