Sending a fax works, and switching to something else means someone has to build the replacement, test it, and take the blame if it goes wrong. That is most of the reason a fax machine is still sitting in a back office somewhere.

Replacing a working system costs money now for a saving later

A fax line is already paid for, already working, and already understood by the staff who use it every day. Moving to email or a secure portal means new software, new training, and a period where things can go wrong while everyone learns the new way. For a large organisation, that upfront cost is easy to put off against a system that, dated as it is, still does the job.

A fax leaves a paper trail nobody has to design

When a document goes by fax, the sending machine prints a transmission confirmation showing the number, the time, and whether it went through. That slip of paper satisfies a good deal of internal audit and evidence checking without anyone having to build a new process to prove a document arrived. Email can do the same job, but trusting it takes a policy decision, and policy decisions take time to reach.

Nobody outside the building is asking for change

A GP surgery, a solicitor's firm, or a court does not lose clients or patients because it still uses fax. The person asking you to send one is not choosing fax over email out of preference. They are following a process that nobody with the authority to rewrite it has had a reason to rewrite.

Each of these organisations ended up needing fax for its own reason, tied to a specific piece of infrastructure or an old procedural rule that nobody has replaced. The reason looks different depending on who is asking.

Courts and tribunals

Court and tribunal paperwork sometimes lists a fax number alongside a postal address, particularly for urgent applications or for serving documents on the other side of a case. Where a matter still runs on a paper file, fax fits into that process without anyone having to build a new digital route between two systems that were never connected.

Solicitors

A solicitor may be asking for a fax because the other side in a transaction, a land registry, or a court does. Conveyancing in particular has long relied on a dated, printed record of exactly when a document was sent, and a fax transmission confirmation gives that in a way an ordinary email does not automatically produce. There is more on how that compares with an email delivery receipt in Is fax more secure than email?.

GP surgeries

A GP surgery and a hospital department are not always on the same secure system, so fax became the method that works regardless of which software either end is running. Referral letters and discharge summaries move between departments that were never linked digitally, and fax remains the one route both sides can use without extra setup.

HMRC

Some HMRC forms and specific teams still list a fax number, usually where a paper record needs to reach a team that has not been brought into an online submission service. The requirement is often limited to that one process, which is worth checking directly before you assume you have to fax anything. See Do I actually need to send a fax? for how to ask.

If a US-based employer or client has asked you to fax a form, the reason usually sits inside their own systems. American healthcare, legal, and HR paperwork was built around fax decades ago, and a lot of it has never been rebuilt around anything else.

Fax and US healthcare paperwork

US medical and insurance providers have long treated fax as an accepted way to move patient records and consent forms between organisations. If your employer is asking you to fax a signed medical release, a benefits enrolment form, or a doctor's note for a US health plan, it is because the provider on the other end still processes incoming paperwork by fax.

Fax in US HR and background checks

Onboarding for a US employer often involves forms that get routed to a background check company, a reference verifier, or a payroll provider, and those third parties are frequently the ones still asking for fax specifically. Your employer may not have a choice either. They are passing on a requirement set by whichever vendor handles that part of the process.

Fax and US legal or contract paperwork

Some US law firms and HR departments still use fax as a way of showing that a signed document arrived from a specific, traceable line, in the same way a posted letter shows an address. It is a habit built into older compliance processes.

None of this means you need a fax machine to satisfy the request. If you are sending a fax to a US number from the UK, the practical steps are the same as any other international fax, and it is worth checking the guide on sending a fax internationally from the UK before you do anything else. If the concern is what happens to the document once it lands on a shared machine at the other end, that is covered separately in the guide on fax security.

Some organisations have moved away from fax. Others haven't got round to it. There's no single point where fax got switched off across the public sector or the professions, because each organisation runs its own systems and makes its own decision about when to replace them.

Where a move has happened, it's usually toward one of a small number of alternatives: a secure portal where you upload a document and log in to prove who you are, an encrypted email address set up specifically for sensitive correspondence, or a case management system that lets a solicitor or a court handle documents electronically from start to finish. None of these are exotic. They're the same idea as fax, proving a document arrived from a particular sender, without the phone line.

Why it happens unevenly

Replacing a fax number with something else takes money, and it takes someone inside the organisation deciding it's worth doing now. A large solicitors' firm with an IT department might make that change quickly. A small GP surgery, a court office running an older case system, or a department that only receives the occasional fax has less reason to prioritise it. That's the whole explanation. It isn't that fax works better for them.

The practical upshot is that you can't assume a fax requirement has quietly gone away just because it feels outdated. The only way to know is to ask the specific organisation what they currently accept, and whether a signed PDF by email or a portal upload would do instead. That question, and what counts as a reasonable answer, is covered in more detail on the page about working out whether you actually need to send a fax.