Applying to one specific course instead of an undecided major is the single biggest structural difference between a UK/Ireland degree and a US one -- and "can I just change my mind after I start" is the question that difference actually raises. The honest answer: sometimes, but it's a discretionary request your department can simply turn down, not a form you fill out.
Changing course at the same university: a real window, not an open door
Every UK university sets its own policy, and they're stricter than most US applicants expect. At the University of Nottingham, changing course without repeating a year can only happen in the first three weeks of the session, at the end of the Autumn semester, or at the end of the full session -- and the policy states plainly: "there is no requirement on Schools to agree to a request for a course change, and Schools are free to turn down such requests." At the University of Westminster, the window is even tighter -- a transfer must normally happen within the first two weeks of the academic year for a new student, or at the end of the year for a continuing one -- and any approval is "subject to the requirements of the academic regulations and academic approval," not automatic. Both schools also flag a real, easy-to-miss consequence: switching course can have funding and, for international students, visa implications that a routine major change in the US simply doesn't carry.
Transferring to a different university entirely
This runs through UCAS, not the schools directly. Per UCAS's own guidance, there's no guarantee of a transfer to another provider, even for a very similar course -- you contact the university directly to gauge interest first, and only proceed to a formal UCAS process if they're willing. Advanced standing (entering directly into year two or three) is sometimes possible if you've already covered equivalent content elsewhere, but it's case-by-case, not a standard pathway, and it's not normally possible to transfer at all beyond year two of a degree.
Why "biology to zoology" is easy and "biology to law" isn't
The real mechanic behind all of this is module overlap, not administrative friction for its own sake. Nottingham's policy allows a same-stage transfer specifically when a student "has already taken all the modules which they are expected to have taken by this point" in the new course -- which is realistic for two closely related subjects, and effectively impossible between two unrelated ones. Switching into a course that requires prerequisites you never took typically means either restarting from year one or petitioning to prove you've separately met those learning outcomes some other way. This is the concrete version of what our piece on applying abroad means by "switching subjects after you've started is a real, often difficult process, not a routine advising conversation" -- it's not vague caution, it's a specific structural fact tied to how UK degrees are built module-by-module around one subject from day one.
What this means for you
- Don't assume "I'll just switch later" is a backup plan -- it's a discretionary request with a real, often 2-3 week deadline, and your department can simply say no.
- A same-subject-family switch (biology to zoology, economics to finance) is realistic; an unrelated switch (biology to law) usually means starting over, because of how much course content the two paths don't share.
- Transferring universities is harder than transferring courses within one -- it runs through UCAS with no guarantee, isn't normally possible after year two, and requires the receiving university's willingness before anything formal starts.
- Check funding and visa implications before requesting any change, not after -- both schools covered here flag this explicitly, and it's a real consequence a US major change doesn't carry.
- This is exactly why being reasonably sure of your subject before applying matters more abroad than at home -- see the full breakdown of every real tradeoff in applying to the UK or Ireland for how this fits with the other structural differences (cost, financial aid, degree recognition) that come with the same 3-year, single-subject model.