Prerequisite Planning

Part of Building the Foundation. The premed prerequisites are chains: each course unlocks the next, most of the chain has to be finished before you sit the MCAT, and one missed link costs you a year, not a course.

The short version

Pick your MCAT date first, then build the course schedule backward from it. Every prerequisite the exam tests has to be behind you by then.

That single move prevents nearly every disaster on this page, and it takes an afternoon in your first year. If you're already past your first year, it still works. It just has fewer semesters to play with.

The courses, and which ones the exam tests

Requirements vary by school, so confirm your targets in the AAMC's Medical School Admission Requirements database. The set most MD programs expect:¹

Course	Typical length	On the MCAT?
Biology with lab	1 year	Yes
General chemistry with lab	1 year	Yes
Organic chemistry with lab	1 year	Yes
Physics with lab	1 year	Yes
Biochemistry	1 semester	Yes, heavily
Psychology	1 semester	Yes
Sociology	1 semester	Yes
Math or statistics	1–2 semesters	Underlies several sections
English or writing	~1 year	Supports reading and writing

Some schools have replaced the course list with a statement of competencies.¹ That changes the paperwork and leaves the preparation alone. The courses above are still what gets you through the exam.

A scheduling note that pays for itself: statistics counts toward your science GPA and psychology and sociology don't, which decides which semester to put each in. GPA Strategy & Recovery has the full classification.

The chains you cannot break

General chemistry → organic chemistry → biochemistry. Three courses, at least three semesters, strictly in order. Biochemistry sits at the far end and usually wants biology as well, which is why it lands in junior year and why it is the course most often missing when someone arrives at their MCAT date.
Biology → biochemistry. Biology is commonly a co-requisite or prerequisite for it.
Physics normally stands alone, sometimes wanting a semester of math. That flexibility is exactly why it gets postponed until there is no room left.
Psychology and sociology have no prerequisites and are easy to schedule at any point. They are also both tested, so they get forgotten and then taken after the exam, which is too late to help.

Biochemistry, psychology, and sociology break more timelines than anything else, for the same reason: none of them feels urgent until it is.

Build the map backward

Decide when you intend to test. Then place every tested course before that date. Everything else follows.

One date sits behind the test date and is easy to miss. The application opens in early May and most people submit in late May or June, and then verification takes weeks. So for a no-gap-year applicant, a March or April test that scores in time to submit in June works; a June test does not, because the score arrives a month after everyone else has already applied into a rolling cycle. Your MCAT date is really being chosen by the submission window, not the other way around. When to Take It & Scheduling has the calendar in full.

Applying straight through, no gap year. You'll test in the spring of junior year, so every science prerequisite plus biochemistry, psychology, and sociology has to be done by then.

Year 1: biology I and II, general chemistry I and II, plus math and English
Year 2: organic chemistry I and II, physics I and II, plus psychology
Year 3 fall: biochemistry, sociology, statistics → MCAT in spring of year 3
Year 3 spring through year 4: apply, finish the degree, upper-level electives

That schedule contains two lab sciences in most semesters, which is a real load. How much paid work fits alongside it is arithmetic, and it is worth doing before you register, while the schedule can still change.

A four-credit science with a lab runs about four hours of lecture and three of lab, plus eight to twelve hours of work outside both. Two of them lands somewhere near thirty hours a week before any of your other courses. Put your job next to that number and look at what is left of the week. If nothing in it is unscheduled, spacing is the thing to change: one lab science a semester across five years, or four years plus a gap year, is the same degree with a GPA that survives it.

Taking a gap year. You get a whole extra year of room, and spend it on spacing. Test in the summer after junior year or in senior year, put one lab science per semester instead of two, and keep the GPA that carries the application. If you're working through school, this isn't the compromise version of the plan. It is the better one, and a large share of applicants take a gap year. Gap Year(s) covers what belongs in it.

Transferring in from a two-year college. Assume the chain starts over on arrival for anything that didn't transfer cleanly, and build from there rather than from your total credit count. The next section is about that.

Starting at a community college, or transferring in

This is the most under-explained situation in premed course planning, and it has its own page: Community College & Transfer covers the articulation agreement and how to find yours, the difference between a course transferring for credit and transferring as the prerequisite, why the rumor that community college disqualifies you is false, and the free AAMC report listing every school's stated policy. It also carries the fact that decides the most: your community college grades are calculated into your AMCAS GPA whether or not your university took them.

This one is a question about chains.

Time the transfer to land in the gap between chains. Transferring after finishing general chemistry is clean. Transferring between organic chemistry I and II isn't, because two schools' sequences rarely line up and you can end up repeating or having a gap in the middle of a year-long course.

When a chain breaks

A withdrawal or a failing grade in a chain course takes every course behind it down with it.

Here is what that actually looks like. You withdraw from organic chemistry I in the fall. Your school teaches organic chemistry I in fall only, so the retake is a full year away. Organic II moves to the following spring, biochemistry to the year after that, and your MCAT date moves with it. One semester's setback, twelve months of consequence.

Three things reduce the damage, and all of them work better the earlier you act.

Find out immediately whether the course runs off-cycle. Many schools offer at least one chain course in summer, or in the opposite semester, precisely because this happens. Some let you take it at another institution with prior approval. Asking in November is worth much more than asking in May.

Know the withdrawal deadline, and call financial aid before you use it. A withdrawal is excluded from your application GPA, while a failing grade is averaged in permanently, and both cost you the same semester of sequence.² So on the application, a W taken on time is the cheaper outcome.

On your finances it may not be, and this is the part that gets left out of the advice. Dropping a four-credit science can put you below full-time, and below full-time can prorate or stop a Pell disbursement, break satisfactory academic progress, void a scholarship with a credit-hour floor, trigger repayment of aid already disbursed, end eligibility for a student health plan or a parent's coverage, and for an international student on an F-1 visa break status outright. Ask your financial aid office what a withdrawal does to your specific package before the deadline, not after. That call takes ten minutes and it is the single highest-return phone call in this article.

Also find out whether your school records withdrawals as failing grades after a certain date. That is the date that actually matters, and you want it in hand early.

Repeat, but understand what repeating does. Retaking replaces nothing. Every attempt is averaged into your application GPA on all three services.² You retake because you need the material for the MCAT or because the next course requires a minimum grade, not because the first grade disappears.

If you start below the sequence

Some students arrive placed into pre-college algebra, or into a chemistry course that is a prerequisite for general chemistry, or into developmental writing. That is a common outcome of the schools people are sent to, not a verdict on them, and it has one concrete consequence worth planning around.

Your chain starts a semester or two later than the four-year map above assumes. Everything downstream moves with it, and the honest result is usually that the test lands after graduation.

Plan for that from the start instead of discovering it in year three. A five-year path, or four years plus a gap year, is an ordinary shape and reads as nothing at all on an application. What reads badly is the version where a student tries to compress the same chain into the remaining time and stacks three sciences in a semester to do it. That trades a year you were worried about for a GPA you can't repair.

Online courses, AP credit, and the rest of the fine print

Online coursework. School policies moved substantially after 2020, and many programs that once refused online prerequisites, including online labs, now accept them. Others still don't, and a few draw the line at the lab specifically. There is no universal answer, so check your target schools' entries directly.¹

AP credit. Some schools won't let AP credit satisfy a prerequisite. The usual remedy is taking upper-level coursework in that subject instead, which is often the better preparation anyway, since the MCAT tests the material regardless of how you skipped it. Verify before you rely on placing out.¹

Summer courses are a legitimate way to catch up or to unstack a heavy semester. Two things to check first: that your target schools accept them and that the credit satisfies the prerequisite itself, and that you can pay for them. Pell and most institutional aid frequently do not extend to summer terms, or extend only if you carry enough credits, so a summer plan can quietly become an out-of-pocket plan.

Don't stack two lab sciences if you can avoid it, and especially not while working substantial hours. This is the single most common self-inflicted GPA injury in the stage, and it is one of the few premed problems that is entirely a scheduling decision.

If you need accommodations, start now

If you have a disability, a chronic illness, or a mental health condition that affects how you take exams, register with your campus disability services office in your first weeks, while nothing has gone wrong yet.

The immediate reason is that accommodations affect course load and pacing, which is what this whole page is about. The reason people miss is downstream: MCAT accommodations are a separate application to the AAMC, they require documentation and a history of accommodation, and the review takes weeks to months. A student who first thinks about this two months before their test date usually cannot get it in time. Establishing accommodations in your first or second year is what makes that possible later.

What belongs to other pages

How your GPA is recalculated, which courses count as science, and what a repeated course does to the number are GPA Strategy & Recovery. Whether your major collides with this sequence is Choosing a Major. When to actually sit the exam, and what a study calendar looks like around these courses, is When to Take It & Scheduling. The two-year college route, and the other longer shapes this can take, is Detours & Off-Ramps.

Common mistakes

Not building the map at all, then finding the gap in junior year when it is expensive.
Leaving biochemistry, psychology, or sociology until after the MCAT. All three are tested.
Postponing physics because it has no prerequisites, until there is nowhere left to put it.
Stacking two lab sciences in a semester you're also working through.
Assuming transfer credit satisfies the prerequisite, when it may only grant credit.
Transferring in the middle of a year-long sequence.
Leaving no slack, so that one setback cascades through everything after it.

Where this fits on the Road

This page decides what you take. GPA Strategy & Recovery decides what the resulting number means, and the two should be read together. Once the chain is mapped, When to Take It & Scheduling is where the MCAT date you planned backward from gets chosen properly.

References

Prerequisite lists, AP and transfer credit policies, online-course acceptance, and competency requirements are set per school and change. Verify against the current MSAR and your own registrar before finalizing a plan. Last reviewed: 2026-08-06

Prerequisite variation by school, the AAMC Premed Competencies framing, and per-school policies on AP credit, community-college coursework, and online courses. Verify individual schools in the Medical School Admission Requirements database. https://students-residents.aamc.org/medical-school-admission-requirements/admission-requirements and https://students-residents.aamc.org/real-stories-demonstrating-premed-competencies/premed-competencies-entering-medical-students ↩ ↩² ↩³ ↩⁴
AMCAS counts every attempt of a repeated course, and withdrawals are excluded from GPA calculation unless the institution records them as failing grades. AMCAS grade calculation and special course types. https://students-residents.aamc.org/apply-medical-school-amcas/publication-chapters/grades-factored-amcas-gpa-calculations and https://students-residents.aamc.org/apply-medical-school-amcas/publication-chapters/special-course-types ↩ ↩²