Which Edexcel IAL Biology or Chemistry Unit Do You Need for January 2027? Unit Codes, Dates and a 5-Question Checklist

It's been more than twenty years since I started teaching Biology and Chemistry to Edexcel and Cambridge mark schemes, and every October the same message arrives: "Sir, which unit do I enter for January?" The question looks simple. It is not. Enter the wrong unit and you sit a paper you haven't finished learning. Forget one code and your result never appears. So here is the whole decision, step by step, with the dates and the rules from Pearson's own documents.

What do the IAL unit codes WBI11–WBI16 and WCH11–WCH16 mean?

A unit code tells you three things: W means International A Level, BI or CH means Biology or Chemistry, and the last digit is the unit number — Units 1 to 3 make up the AS, Units 4 to 6 make up the A2, and all six together make the full IAL. Units 3 and 6 are written practical-skills papers; there is no lab exam in this qualification.

Why does the weighting matter? Because Units 1, 2, 4 and 5 each carry 20% of the full IAL, while Units 3 and 6 carry 10% each. In other words, a theory unit is worth twice a practical unit when the grade is added up. That is the whole reason the Pearson Biology unit structure gives the theory papers 80 or 90 marks and the practical papers 50. Chemistry follows the same shape in the Pearson Chemistry unit structure.

Code	Unit	Level	Paper	Marks · length	Share of full IAL
WBI11	Biology 1: Molecules, Diet, Transport and Health	AS	Theory	80 · 1h 30m	20%
WBI12	Biology 2: Cells, Development, Biodiversity and Conservation	AS	Theory	80 · 1h 30m	20%
WBI13	Biology 3: Practical Skills in Biology I	AS	Practical (written)	50 · 1h 20m	10%
WBI14	Biology 4: Energy, Environment, Microbiology and Immunity	A2	Theory	90 · 1h 45m	20%
WBI15	Biology 5: Respiration, Internal Environment, Coordination and Gene Technology	A2	Theory	90 · 1h 45m	20%
WBI16	Biology 6: Practical Skills in Biology II	A2	Practical (written)	50 · 1h 20m	10%
WCH11	Chemistry 1: Structure, Bonding and Introduction to Organic Chemistry	AS	Theory	80 · 1h 30m	20%
WCH12	Chemistry 2: Energetics, Group Chemistry, Halogenoalkanes and Alcohols	AS	Theory	80 · 1h 30m	20%
WCH13	Chemistry 3: Practical Skills in Chemistry I	AS	Practical (written)	50 · 1h 20m	10%
WCH14	Chemistry 4: Rates, Equilibria and Further Organic Chemistry	A2	Theory	90 · 1h 45m	20%
WCH15	Chemistry 5: Transition Metals and Organic Nitrogen Chemistry	A2	Theory	90 · 1h 45m	20%
WCH16	Chemistry 6: Practical Skills in Chemistry II	A2	Practical (written)	50 · 1h 20m	10%

Now, the unit code is what you enter. It is not what gives you a certificate. For that you need a second code, what we call the cash-in code: XBI11 for AS Biology, YBI11 for the full IAL in Biology, XCH11 for AS Chemistry and YCH11 for the full IAL in Chemistry. The Pearson Information Manual for 2026/27 puts it in one line: no grade can be issued unless the cash-in code is entered. From what I've heard from students, "my result is missing" is nearly always a missing cash-in, not a missing paper.

Which IAL Biology and Chemistry units run in January 2027?

All twelve units run in January 2027 — WBI11 to WBI16 and WCH11 to WCH16 — and that includes both practical papers, Unit 3 and Unit 6. The series opens on Friday 8 January and every Biology and Chemistry paper is finished by Friday 22 January.

Many students still believe the practical papers are summer-only. They are not. The January 2027 IAL timetable lists every one of them, and the Information Manual marks every unit "Yes" for the January series. Here are the dates, as published.

Date	Code	Unit	Session	Length
Fri 8 Jan	WBI11	Biology Unit 1	Afternoon	1h 30m
Mon 11 Jan	WCH11	Chemistry Unit 1	Morning	1h 30m
Tue 12 Jan	WBI12	Biology Unit 2	Morning	1h 30m
Tue 12 Jan	WCH12	Chemistry Unit 2	Afternoon	1h 30m
Thu 14 Jan	WBI13	Biology Unit 3	Morning	1h 20m
Thu 14 Jan	WCH13	Chemistry Unit 3	Afternoon	1h 20m
Mon 18 Jan	WBI14	Biology Unit 4	Morning	1h 45m
Mon 18 Jan	WCH14	Chemistry Unit 4	Afternoon	1h 45m
Wed 20 Jan	WBI15	Biology Unit 5	Morning	1h 45m
Thu 21 Jan	WCH15	Chemistry Unit 5	Morning	1h 45m
Fri 22 Jan	WBI16	Biology Unit 6	Morning	1h 20m
Fri 22 Jan	WCH16	Chemistry Unit 6	Afternoon	1h 20m

Two pressure points to see now, not in January. First, if you sit both sciences you have four double days: 12, 14, 18 and 22 January, Biology in the morning and Chemistry in the afternoon. Second, Chemistry has two back-to-back pairs, WCH11 then WCH12 on 11 and 12 January, and WCH15 then WCH16 on 21 and 22 January. Biology has no back-to-back pair at all. The full day-by-day plan, with start times for your time zone, is in the Edexcel IAL January 2027 timetable for Biology and Chemistry.

You are entering late — here is what that costs now

The standard entry deadline for January 2027 was 16 October 2026; from 17 October the unit fee is doubled, and from 14 November it is trebled. You can still enter. You simply pay more, and your centre's own window may close before Pearson's.

Those are Pearson's dates, from the 2026/27 key dates manual, which also starts charging amendment fees from 14 November if you change a unit. But here is the part nobody tells you: the British Council office you register through runs its own calendar, and it runs earlier. British Council Oman closes its late stage 1 window on 6 November 2026. British Council Pakistan lists 6 November for late stage and 20 December for late stage 2. British Council Sri Lanka's January 2027 information sheet gives 6 November for late stage 1 and 11 December for late stage 2. British Council Bangladesh closed late registration on 28 October. So what is the real deadline for the doubled fee? For most of you, this Friday, 6 November. After that you are in the treble band, if your office still accepts you at all.

In money, the UAE is the clearest public example. The British Council UAE January 2026 price list charged AED 550 for one Biology or Chemistry unit at the standard stage, AED 1,165 at low late fee and AED 1,780 at high late fee, with the cash-in free on time and AED 95 late. In Kuwait, Qatar and Saudi Arabia the fees sit inside the School Registration System once you log in, and British Council Kuwait confirms the same rule: register after the normal stage and a penalty applies. The ratio is what matters, and the ratio is the same everywhere: roughly double, then roughly treble.

Which units should you sit in January 2027? Five questions

Most students should sit one unit in January and the rest in June — Unit 1 if you are AS, Unit 4 if you are A2 — and only add a second unit if it is a resit of a paper you have already sat. That is the pattern I see every year, and it is the pattern that produces the best June results.

Why one unit? Two reasons. For many of you the January series comes very close to the October one, so there is simply no room to prepare two new units properly. And for AS students there is a bigger reason: you need to experience one real exam first. One paper teaches you the pacing, the command words and the bubble sheet. After that, June feels familiar. That is why the majority of my students take Unit 1 or Unit 4 in January and nothing else. Now ask yourself these five questions.

1. Is this a first sitting or a resit?

If it is a resit, January is the best series you will get. Any unit can be resat, and the Information Manual is clear that the better of your two most recent non-absent attempts is the one that counts. Students who resit tend to jump a grade, not because they learned more biology, but because they have already lived the pacing of that paper and they know exactly what went wrong. A resit is basically a gap-filling exercise. So here is what you do: ask your centre for your marked script, go through it question by question, and work only on the marks you lost. Then use the IAL UMS converter to see how many raw marks separate you from the next grade. Pick the unit with the biggest UMS gap. That is where the resit pays.

2. Have you finished the AS content?

Can you sit Unit 3 before Unit 2? No. I strongly don't recommend it. In Biology nearly half of the Unit 3 practicals come from Unit 2. In Chemistry it is a definite no: most of the Unit 3 practicals are from Unit 2, with only a few from Unit 1. The Pearson Biology unit structure says Unit 3 assesses the techniques developed in Units 1 and 2, and Unit 6 the techniques from Units 1, 2, 4 and 5; Chemistry's Unit 6 draws on Units 4 and 5. So the practical paper always comes last in its level. Check what you have covered against the AS Biology syllabus checklist, the A2 Biology syllabus checklist or the AS Chemistry syllabus checklist before you enter anything.

3. Are you sitting both sciences?

Then the four double days decide your December. My advice is simple: have both papers fully prepared before the double day, leave the day before for minor revision only, and treat the exam day itself as recovery, nothing else. Why? Because of the gap. In many centres the two papers are given back-to-back; in many cases you do not get a proper break, and you may not even be allowed to leave the room between them. If you walk in on 12 January still learning Chemistry Unit 2, the Biology paper in the morning will take the energy you needed in the afternoon.

4. Does a paper clash with another subject?

Look at the timetable now. If one of your units shares a session with another subject, tell your exams officer this week, not in January. Centres arrange clashes with a supervised break, but the arrangement has to be in place before the high late fee and amendment date on 14 November.

5. Should you move a unit to June?

Here is my rule of thumb. Move the unit whose teaching finishes last. Keep in January the one you have already sat once, because a resit needs the least new learning. And never pull Unit 6 forward to January "to get it over with". Unit 6 is the widest paper in the qualification; it reaches back into every theory unit. If you want to know which Chemistry unit frightens students most, I've written up the hardest IAL Chemistry unit separately. For the resit-or-move-on decision after October results, read IAL October results and the January entry — but note that October results arrive on 21 January, after every January paper except Unit 6, so they can only shape your June entries, not January.

The 2027 specification clock: what sitting in January commits you to

Every January 2027 entry is on the 2018 (legacy) specification; Pearson's new 2027 Biology and Chemistry specification first sits in June 2028, and units from the two cannot be mixed. If you start on the legacy units now, you finish on the legacy units.

What does that mean in dates? According to Pearson's IAL key dates for the 2027 qualification, the legacy AS runs through January 2027, June 2027 and October 2027, with January 2028 as a resit-only series. The legacy full IAL runs through to June 2029, with that final series marked resit-only. Pearson tells centres that learners on the current specification should complete the current specification. So if you are an AS student entering Unit 1 this January, plan to finish Units 2 and 3 by June or October 2027, and all of A2 by June 2029 at the very latest. For nearly all of you that is no problem. For a student who is thinking of pausing a year, it is the one date to write down.

Three worked cases

These are built from the pattern of my own January classes, not from any one student.

Case 1 — AS Biology, first sitting. Taught Unit 1 by December, Unit 2 half done. Enter WBI11 only in January. Sit WBI12 and WBI13 in June, enter XBI11 with them. Why not WBI12 in January too? Because half of it isn't taught, and a weak first paper costs more confidence than it saves time.

Case 2 — A2 Chemistry, resitting Unit 2. Scored a C on WCH12 in June, now in A2. Enter WCH12 as a resit plus WCH14 in January, and re-enter XCH11 with the resit, because the three AS units are already complete. Leave WCH15 and WCH16 for June, and enter YCH11 then, when the last A2 unit is sat. The UMS converter will show whether the Unit 2 gap is worth it; usually it is, because Unit 2 carries twice the weight of Unit 3. Remember two rules from the Pearson entries guidance: a resit must carry its cash-in code again, and the full IAL code is never entered until all six units are in.

Case 3 — Biology and Chemistry together, deciding what to defer. A2 student, both subjects, three A2 units each still to sit. Enter WBI14 and WCH14 in January; one double day, 18 January, and nothing else. Defer Units 5 and 6 in both subjects to June. Six A2 papers across four double days in January is the plan I see go wrong most often.

Entry checklist — six ticks before you pay

1. The unit code for each paper you will sit (W-codes above).
2. The cash-in code — XBI11 or XCH11 once Units 1 to 3 are all entered, YBI11 or YCH11 only once all six are — and the same code again whenever you resit a unit inside it.
3. Your centre's own late-stage date, which for most British Council offices is 6 November, not 14 November.
4. Pearson's high late fee and amendment date, 14 November, after which a change of unit costs extra.
5. Any clash reported to the exams officer in writing.
6. Your ID and UCI number. Use the same UCI as your previous series, or your banked units will not join up. Private candidates enter through an approved centre — the Information Manual confirms you cannot enter directly with Pearson.

Which course covers which unit?

Pick the unit, then pick the matching material. Every IAL course, live class and solved-papers pack is 15% off with code JAN27 until 30 November.

Unit	What you need	Price
WBI11 / WCH11	Unit 1 course · Unit 1 solved papers — inside the AS Biology course or the AS Chemistry course	$100 · $40
WBI12 / WCH12	Unit 2 course · Unit 2 solved papers	$100 · $40
WBI13 / WCH13	Units 2 + 3 course, practical training included	$150
WBI14	Biology Unit 4 WBI14 course · solved papers	$100 · $40
WBI15	Biology Unit 5 WBI15 course · solved papers	$100 · $40
WBI16	Biology Units 5 + 6 course, practical training included	$150
WCH14 / WCH15 / WCH16	A2 Chemistry notes + solved papers for Unit 4, Unit 5 and Unit 6	$100
All three AS units	Full AS course, self-paced	$250

If you would rather be taught live, the IAL Biology live classes and IAL Chemistry live classes run at 5 pm Kuwait time, and I confirm your timetable within 12 hours of joining. For the January papers themselves, the solved IAL past papers are the fastest way to see what a full-mark answer looks like, and the IAL Biology and Chemistry notes eBooks are updated after every mark scheme and examiner report.

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FAQ

Can I sit IAL Unit 3 in January?
Yes — WBI13 and WCH13 both run on Thursday 14 January 2027, and every unit from 1 to 6 is available in the January series. Just don't sit it before you have finished Unit 2, because most of its practicals come from there.

Can I resit only one IAL unit?
Yes. Edexcel IAL is modular, so you re-enter the single unit you want to improve, and the better of your two most recent attempts counts towards the grade.

Do I need a cash-in code for a resit?
Yes, if the resit is part of a qualification you have completed or are completing — re-enter the same cash-in code with the resit unit, or the new mark will not be aggregated into your grade. If you are still unsure which units to enter, message me on WhatsApp or email [email protected].

When are the January 2027 IAL results?
Pearson releases January 2027 IAL results to centres on 3 March 2027 and to candidates on 4 March 2027. Certificates follow by April.

That's all for today. I hope that this was helpful and I wish you all best of luck in your January exam.

Checked against Pearson's January 2027 FINAL timetable and the 2026/27 Information Manual on 3 November 2026.