Reference · UK professional bodies
The largest UK professional bodies and trade associations
Twenty professional bodies and eleven trade associations, ranked by the membership each one publishes or files.
Every figure is dated and read from the body’s own annual report or accounts, or from a regulator’s register. No primary figure, no row.
Counted from annual reports, accounts, regulators’ registers, union returns
How a figure gets inthe rule
- 01The body’s own reportannual report or accountsREAD
- 02Or a regulator’s recordSRA register, union returnCHECK
- 03The date it applies toyear end or report dateDATE
- 04Who is countedstudents, learners, affiliatesBASIS
- 05No primary figurethe body is left outEXCLUDE
Every rowprimary-sourced and dated
01/ the ranking
The largest UK professional bodies, by membership
Twenty UK professional bodies, ranked by the membership each publishes or files. Filter by sector or size, or sort by name or by the newest figure.
A professional body is an organisation of individuals in one occupation that advances knowledge in it and maintains standards of conduct and competence among its members — the objects HMRC tests before approving a body for tax relief (ITEPA 2003, s.344). The Royal College of Nursing is the largest in the UK by a distance: more than 570,000 members at the end of 2024.
Read the basis line before comparing rows. ACCA and ICAEW count qualified members and publish students separately; CMI counts members and learners together; four bodies here are also trade unions and file a membership return every year. Where a body is global, the figure is global and the row says so.
Showing 20 of 20
Sector
Size
Top ten by stated membership
- RCN570,000+
- ACCA257,956
- CMI230,171
- BMA194,147
- Law Society178,428
- ICAEW172,273
- CIPDc.165,000
- IET156,000+
- CII121,038
- RICS113,485
Sector labels are ours. Every figure links to the document it was read from; the method explains what was left out and why.
02/ trade associations
The largest UK trade associations
Eleven UK trade associations with a membership count in their own report or accounts, or in a return to the Certification Officer.
A trade association’s members are businesses, not individuals — the first of three essential characteristics the Trade Association Forum sets out, with members controlling the governing body and sharing a common interest. So its headcount is small beside a professional body’s and its reach is wide: the CBI’s 850 direct members sit alongside more than 150,000 members of the trade associations within it.
There is no definitive map of the sector. TAF keeps records of close to 1,000 trade associations active in the UK, and counts just over 180 of them as members, representing close to 200,000 businesses.
Showing 11 of 11
Sector
Size
- CBI850Direct members: 850. Businesses represented: 150,000+.
- Make UK2,055Direct members: 2,055. Businesses represented: 20,000.
- TAF180+Direct members: 180+. Businesses represented: c.200,000.
Direct members vs the businesses each says it represents: CBI annual report 2024; EEF Ltd AR27 2024 and Make UK Impact Report 2025; TAF.
The FSB, UKHospitality and SMMT are not in the table: none of the documents we could fetch states a dated membership count in an annual report, accounts or a regulator’s return. See the method.
03/ what it means
What membership of a professional body means
In the UK the working test is HMRC’s: a body it has approved, on List 3, for tax relief on members’ subscriptions.
HMRC’s List 3 names the approved professional organisations and learned societies. The test behind it is statutory: a body can be approved only if it is not of a mainly local character, does not operate for profit, and directs its activities wholly or mainly to advancing knowledge, maintaining standards of conduct and competence in a profession, or indemnifying members against professional claims (ITEPA 2003, s.344).
For the member, membership usually brings a grade (student, associate, member, fellow), a code of conduct with discipline behind it, and continuing professional development. In some professions it is also the way onto a register: engineers on the Engineering Council’s national register of around 215,000 must, in most cases, be members of a licensed institution (Engineering Council).
Membership and regulation are not always one body. Solicitors in England and Wales hold practising certificates from the Solicitors Regulation Authority; the Law Society is their professional body. What members get for the fee is a separate question, covered on member benefits.
Can you claim tax relief on your subscription?
01Is the body on HMRC’s List 3?
02Did you pay the subscription yourself?
03Is membership relevant to your job?
04Is it an annual subscription, not life membership?
Answer the 4 questions to see where you stand.
Rules from GOV.UK, List 3. A guide, not tax advice.
BCS membership by grade, 31 Aug 2024
- Members46,476
- Students14,941
- Associate members3,697
- Fellows3,598
- Affiliates2,108
04/ kinds of body
Professional body or trade association: the difference
Who joins decides the kind of body. Individuals in a profession make a professional body; businesses make a trade association; “membership organisation” covers both and everything else people join.
The official codes draw the same lines. Companies House classifies every company by SIC code: 94110 for business and employers membership organisations, 94120 for professional membership organisations, 94200 for trade unions and 94990 for other membership organisations.
Employment law adds one more. An employers’ association is an organisation of employers whose principal purposes include regulating relations with workers or trade unions (TULRCA 1992, s.122). The Certification Officer lists 36 of them — the NFU, EEF (Make UK) and the Federation of Master Builders among the ones above — and 131 trade unions, which is why the RCN, BMA, CSP and RCM file a membership return every year (Certification Officer, 2025–26).
The lines blur. TAF notes that some professional bodies also regulate their field, and that some employers’ organisations are trade associations too. For how the marketing differs, see professional body marketing and trade association marketing.
→ A membership organisation of individuals.
→ A membership organisation of firms.
05/ growth
How the largest bodies grow
Their own reports name the levers: student pipelines, learner conversion, retention, price and the occasional merger.
ACCA added more than 30,000 members in five years, reaching 257,956 at 31 March 2025, with 530,124 students and affiliates — its “future members” — behind them. The Royal Society of Chemistry grew from 44,408 members in 2020 to a record 61,647 at the end of 2024.
Not every large body is growing. IMechE’s total fell from 110,759 to 108,377 in 2024, mostly through fewer international affiliates; NFU core membership fell from 50,505 in 2023 to 47,336 in 2025, which its accounts put down to contraction in the industry and affordability for smaller farmers.
For the benchmarks behind renewal and first-year retention, see membership marketing statistics and membership retention rate; for the recruitment side, new member acquisition.
RCN · 2024
Free first-year student membership
The RCN made membership free for first-year nursing students; first-year joiners rose 21% in August to October against the same months of 2023.
ICAEW · 2024
Turn students into members
Of 6,348 new ICAEW members in 2024, 5,194 were newly qualified students admitted to membership.
CMI · 2024–25
Convert learners to paying members
Paying CMI membership rose 5.7%; learners converting to paying membership after their studies rose 5% year on year.
CIM · 2024–25
Keep more of the members you have
CIM grew to 25,888 members, driven by a 1.8% improvement in retention.
IoD · 2025
Review the price and keep growing
An IoD pricing review raised revenue per member in 2025, and membership still grew, to 19,686.
CIOB · 2025
Bring a smaller body in
CIOB integrated the Institute of Roofing in 2025 and ended the year with 50,826 members.
CII · 2023–24
Count only real members
A 2023 database review removed around 2% of CII entries as duplicates or unreachable; 2024 then brought its first net increase since 2019.
ACCA members worldwide, at 31 March (thousands)
06/ method
Method: where every number comes from
A body appears only if we could fetch a dated membership figure from its own annual report or accounts, or from a regulator’s register or return.
Each figure was read in the document its row links to, on 28 September 2026, and is shown as that document states it — “more than” and “c.” included. We used the most recent edition we could fetch, so dates differ by body, and financial years end in different months.
We record who is counted. Students, learners, affiliates and retired members are in some totals and not others; the basis line in each row says which. Worldwide figures stay worldwide: most large UK bodies admit members abroad, and only some publish a UK split.
For the professional body sector itself, PARN researches it and TAF is the association of trade associations. MemberWise publishes its own list of the largest UK professional bodies as further reading; this page was compiled separately, from the documents linked above.
Step 1
Shortlist
Large UK-based professional bodies and trade associations.
Step 2
Find the primary
Annual report, accounts, SRA register or a Certification Officer return.
Step 3
Read the figure
Exact wording, the date it applies to, and who it counts.
Step 4
Record the basis
Students, learners, affiliates, worldwide or UK.
Step 5
Or leave it out
No fetchable, dated primary figure means no row.
Checked and left out
- Institution of Civil Engineers: its May 2025 press release says it is approaching 100,000 members; we could not fetch a dated total.
- Federation of Small Businesses: its 2024–25 annual report page gives no membership count.
- UKHospitality: describes the companies and venues it speaks for, not a count from accounts.
- SMMT: its Motor Industry Facts says it represents more than 800 companies; not a figure from accounts.
- AAT and CIPS: no current membership figure in a report we could fetch.
07/ questions
Questions about UK professional bodies
15 minutes · video or phone
Growing a professional body or trade association?
Book 15 minutes on recruitment, renewal and the first-year gap, with a team that works only with membership bodies.
- 0115 minutes, video or phone
- 02Your figures, not a benchmark
- 03Where growth could come from
- 04A plain next step
Pick a day that suits · live availability
Book 15 minutes · no obligation
Growing a membership body?
Recruitment, renewal and the first-year gap, for professional bodies and trade associations.
09/ sources
Every claim, and where it came from
Every membership figure, the document it was read from, and what kind of source it is. Read 28 September 2026.
- Royal College of Nursing — Group Annual Report 2024 (570,000+ members)Own annual report
- ACCA — Annual integrated report 2025 (257,956 members; 530,124 future members)Own annual report
- ACCA — Financial statements 2025 (members 2021–2025)Own accounts
- ACCA — Financial statements 2024 (227,332 members in March 2020)Own accounts
- Chartered Management Institute — Annual Report 2025 (230,171 members and learners)Own annual report
- Chartered Management Institute — AGM minutes, 9 Oct 2025 (paying membership over 33,000)Own governance record
- Certification Officer — BMA annual return AR21, 2024 (194,147)Regulator filing
- Solicitors Regulation Authority — Regulated population statistics (178,428 practising; 214,080 on the roll)Regulator register
- The Law Society — Our history (over 200,000 members)Own statement
- ICAEW — Annual Review 2024 (172,273 members; 38,199 ACA students)Own annual report
- CIPD — Annual report 2024–25 (c.165,000 members)Own annual report
- IET — Annual Report and Accounts 2025 (156,000+ members)Own annual report
- Chartered Insurance Institute — Annual Report 2024 (121,038 members)Own annual report
- Chartered Insurance Institute — AGM minutes, 24 Oct 2024 (2023 database review)Own governance record
- RICS — Standards and Regulation Board annual report 2024 (113,485 members)Own annual report
- RICS — Annual review 2024 (142,032 professionals and trainees)Own annual report
- IMechE — Trustee Board’s report and annual accounts 2024 (108,377)Own annual report
- BCS — Annual report 2024 (70,820, by grade)Own annual report
- Certification Officer — CSP annual return AR21, 2024 (65,165)Regulator filing
- Royal Society of Chemistry — Trustees’ report and financial statements 2024 (61,647)Own annual report
- RIBA — Annual Report and Financial Statements 2024 (57,266)Own annual report
- CIOB — Annual review and accounts 2025 (50,826)Own annual report
- IOSH — Annual report and accounts 2024–25 (50,114)Own annual report
- Certification Officer — RCM annual return AR21, 2024 (48,335)Regulator filing
- Chartered Institute of Marketing — Annual review 2025 (25,888)Own annual report
- Institute of Directors — Annual Report and Accounts 2025 (19,686)Own annual report
- National Farmers’ Union — Accounts 2025 (47,336 core members)Own accounts
- National Farmers’ Union — Financial statement 2024 (48,938; 50,505 in 2023)Own accounts
- Logistics UK — Annual report and accounts 2025 (21,333)Own accounts
- Certification Officer — NFRN annual return AR27, 2024 (8,655)Regulator filing
- Road Haulage Association — Annual Report 2023 (8,256)Own annual report
- Certification Officer — Federation of Master Builders annual returns (6,809 at end 2023)Regulator filing
- Certification Officer — EEF Ltd (Make UK) annual returns (2,055 at end 2024)Regulator filing
- Make UK — Impact Report 2025 (20,000 manufacturers represented)Own report
- techUK — Annual report and financial statements 2024 (1,098)Own accounts
- CBI — Annual report and accounts 2024 (850 members; 150,000+ trade association members)Own annual report
- Home Builders Federation — Signed accounts 2023 (471; 294 full members)Own accounts
- Association of British Insurers — Annual review 2023 (more than 300 firms)Own annual report
- UK Finance — Annual report 2025 (more than 300 firms)Own annual report
- HM Revenue & Customs — Approved professional organisations and learned societies (List 3)Government list
- legislation.gov.uk — Income Tax (Earnings and Pensions) Act 2003, s.344Statute
- legislation.gov.uk — Trade Union and Labour Relations (Consolidation) Act 1992, s.122Statute
- Certification Officer — Annual report 2025–26 (131 trade unions; 36 employers’ associations)Regulator
- Companies House — Standard Industrial Classification codes (94110, 94120, 94200, 94990)Government classification
- Engineering Council — Guide to professional registration (register of around 215,000)Regulator
- Trade Association Forum — About trade associations (close to 1,000 active; 180+ members)Sector body
- PARN — About the Professional Associations Research NetworkSector body
- MemberWise — The 10 largest professional bodies in the UK (further reading)Sector network; compiled independently