A visa in your passport that unlocks others

The flight to a conference in Spain was booked, the bags were packed and cabin-ready. Then a British Airways check-in agent in Johannesburg shook her head and said no. No boarding pass. No Europe.

The reason: connecting through Heathrow on a South African passport, even to a European destination, now requires a UK transit visa. A few months earlier, I had transited through Heathrow without a problem, but this time I was not even offered an option.

I didn’t have a transit visa. I went home, and cancelled everything, since it is impossible to get a UK visa overnight. The double frustration was that I had been scheduled to leave the day before, but my BA flight was delayed to the next morning. Since I would land at Heathrow at night and the connecting flight to Spain would be the following day, I changed my JNB-LHR ticket to an evening time slot a day later. But when I tried to check in, the app kept telling me I could not check in online and had to do so at the airport.

Amid all this backward and forward activity, including half-an-hour with an agent online, one might think the little matter of a transit visa would have been flagged.

Only after cancelling all plans and setting up systems to cover the intended conference virtually, a friend mentioned he had almost had the same problem, but Heathrow had accepted a US visa for transit. I checked the UK Home Office’s own published carrier requirements, and discovered what the BA agent apparently did not know.  

A valid US visa is an officially recognised exemption that allows South African passport holders to transit Heathrow airside, without any UK transit paperwork — regardless of whether the US is on the itinerary.

It goes further. Any South African national who holds a valid visa for Australia, Canada, New Zealand or the United States can use that document to transit airside through the UK to anywhere in the world, without needing a direct airside transit visa.

My US visa was sitting in my older passport through this entire process, but no one had bothered to ask for or suggest it.

And, the Heathrow exemption turns out to be one instance of a much broader principle of a visa for one country allowing access to another. It is a principle with consequences for South African travellers that go well beyond a Heathrow connection.

One stamp, many doors

A number of countries have decided that if another nation’s immigration authorities have already vetted you thoroughly enough to issue a visa, they are willing to rely on that assessment rather than conduct their own. The US, UK, Schengen zone, Canada, Australia and Japan are the countries whose visas carry this credibility.

Their applications demand financial documentation, background checks and, in the American case for a first-time visa, an in-person consular interview that can take weeks to schedule. Other countries have concluded it’s simpler to piggyback on that process than replicate it.

The practical consequence for South Africans is striking, and one example stands out The 2026 FIFA World Cup opens on 11 June at Estadio Azteca in Mexico City, with Mexico’s first match against South Africa. Thousands of South Africans are looking at flights right now, and most assume they need a Mexican visa — which ordinarily they do. I have heard of several South Africans being denied visas in the run-up to the World Cup.

But Mexico waives that requirement entirely for travellers who hold a valid, unexpired visa from the United States, Canada, the United Kingdom, Japan, or a Schengen country. A South African with a current multi-entry US visa can book a flight to Mexico City and gets on it, with no Mexican visa application or additional paperwork of any kind.

Given that the US is also a World Cup co-host, and South Africans need a US visa to enter the USA, the case for obtaining one before the tournament needs little argument. There may be a proviso that it has been used at least once, successfully, to enter the USA prior to using it to enter Mexico, but that may well be sorted out by flight routing.

The conditions

Various countries have introduced similar rules. The requirements across all these arrangements follow the same pattern. The visa must be multiple-entry. A single-entry visa, once used, is spent. It must have been used at least once, meaning there is an actual entry stamp from the issuing country in the passport. A freshly issued visa with no travel history behind it is treated differently in several of these schemes.

In some countries, this could present a problem for holders of a relatively new US visa, since the USA no longer stamps passports on entry.

The visa must remain valid, with many countries requiring at least six months remaining at the time of travel. For UK airside transit specifically, the exemption holds only while you stay within the international terminal. That means it does not allow changing airports, collecting and rechecking bags, or an overnight stop that pushes the onward flight to the following day.

The takeaway

South African citizens have visa-free or visa on arrival access to 100 countries, ranking the passport around 47th in the world. That excludes most of the destinations where major events are held. A valid multi-entry US B1/B2 visa, once it carries an entry stamp from an actual trip to America, is the most powerful ancillary travel document a South African passport holder can carry.

It clears the Heathrow transit hurdle, removes the Mexico visa requirement at a time when thousands of South Africans want to be at the Azteca, and opens a string of other destinations that have decided the Americans have already done their vetting.

The world’s immigration systems are not the series of independent walls they appear to be from a South African passport. A visa from a trusted issuing country often travels further than the country that issued it. That fact rarely appears on an airline’s check-in screen. It certainly did not on mine.