William Buck
Australian/NZ mid-market accounting and advisory network, 130 years old, $200M+ revenue.
On the record
Checkpoint: AFR Top 100 Accounting Firms list, FY2026 revenue and ranking comparison
The call
William Buck isn't at risk of dying, but it's not visibly investing in AI while peers like BDO and Pitcher Partners publicize theirs and grow faster.
William Buck is a mid-sized accounting and tax advisory firm in Australia and New Zealand, owned by its partners and deliberately built to serve smaller and wealthy clients that the Big Four ignore. It is hard to replace because those clients trust relationships built over decades, and the firm holds regulatory licenses others must earn slowly, but the real test is speed: rivals like Pitcher Partners and BDO are already using AI to automate routine tax and audit work, while William Buck has published only one article about AI for clients rather than showing it is using AI internally to cut costs and speed up work. If competitors roll out AI tools faster over the next year or two, partners may earn less money even if the firm survives, because AI will turn routine work into a low-margin commodity.
Why
01
AI pressure: Frontier AI tools (Claude, OpenAI) automating tax prep and reconciliation. AI compresses commodity compliance work; William Buck's public response is one client-education article, not a deployment. Could AI do the core job? Only partly.
02
Bigger players: BDO, Pitcher Partners, Kelly+Partners. Peers are growing faster (BDO +12%, Kelly+Partners +25%) and publicizing AI platform rollouts William Buck hasn't matched. Could a giant copy it? No, they are blocked.
03
What protects it. Big Four are cost-structurally locked out of the mid-market SME/HNW space William Buck owns through decades of relationships and audit licensing.
What would change this call
AFR Top 100 Accounting Firms list (Nov 2026) shows William Buck's revenue growth vs BDO, Pitcher, Kelly+Partners. Whether William Buck is losing relative market share to mid-market peers.
William Buck announces (or fails to announce) an internal frontier-AI deployment within 12-18 months. Whether it is falling behind peers like Pitcher Partners and BDO on AI-driven efficiency.
Another William Buck merger or acquisition announcement, similar to Tregloans 2019. Whether it is matching Kelly+Partners-style consolidation to defend growth.
William Buck announces (or fails to announce) an internal frontier-AI deployment within 12-18 months. Whether it is falling behind peers like Pitcher Partners and BDO on AI-driven efficiency.
Another William Buck merger or acquisition announcement, similar to Tregloans 2019. Whether it is matching Kelly+Partners-style consolidation to defend growth.
Key numbers
- $200M+ FY2025 revenue
- 157 partners, 1,200+ staff
- BDO $606.5M FY2025, +12% YoY
Named risks
- No public evidence of internal frontier-AI deployment while peers scale AI across thousands of staff.
- Revenue growth rate undisclosed and potentially lagging BDO's 12% and Kelly+Partners' 25% FY2025 growth.
- Partnership-equity model limits access to external capital for scaling versus ASX-listed roll-up Kelly+Partners.
- AI-driven commoditization of compliance work (tax prep, reconciliation, audit sampling) could compress fee revenue.
Rivals, as read in July 2026
| Rival | Direction | Evidence |
|---|---|---|
| BDO Australia | gaining on | BDO grew revenue 12% to $606.5m in FY2025 vs William Buck's flat $200m+ disclosure, 2025-11-25 |
| Pitcher Partners | gaining on | Pitcher Partners credits AI investment for securing AFR top-10 ranking, 2025-11-26 |
| Kelly+Partners Group | gaining on | Kelly+Partners grew 25% YoY via acquisition roll-up, ranked 17th AFR Top 100, FY2025 |
| Big Four (Deloitte, KPMG, PwC) | contesting | Deloitte deployed Claude to 470,000 staff and PwC certified 30,000 on Anthropic by May 2026, William Buck has no matching announcement |
Questions people ask
- Is William Buck profitable in 2026?
- William Buck does not publish profit figures, but as a private partnership it reported combined turnover of over $200 million for the year ended 30 June 2025, per its own Transparency Report published October 2025.
- Could AI replace William Buck?
- AI can automate compliance tasks like tax prep and reconciliation, but William Buck's licensed Authorised Audit Company status and decades-long SME/HNW partner relationships are regulatory and trust moats AI cannot assume, as of its October 2025 Transparency Report.
- Who owns William Buck?
- William Buck is a partner-owned network of separately owned member firms across Australia and New Zealand, with no external investors or private equity ownership identified as of its October 2025 Transparency Report.
- Is William Buck's biggest competitor the Big Four?
- No. The Big Four (Deloitte, EY, KPMG, PwC) each earn over A$2 billion in Australian revenue and are structurally priced out of William Buck's mid-market SME segment; true peers are BDO, Pitcher Partners and Kelly+Partners, per AFR's 2025 Top 100 list.
- How fast is William Buck growing compared to rivals?
- William Buck's growth rate is not separately disclosed, but peers reported for FY2025: BDO grew 12% to $606.5 million, Pitcher Partners grew 2% to $355.93 million, and Kelly+Partners grew 25% to $134.6 million, per AFR-linked reporting.
- Has William Buck deployed AI internally like the Big Four?
- William Buck's visible AI activity as of July 2026 is limited to a March 2025 client-education article on AI for business owners, versus Deloitte's 470,000-staff Claude rollout and PwC's May 2026 Anthropic certification of 30,000 staff.
Timeline
- 2026-07-15William Buck partnership expands to 157 partners with seven new appointments
- 2026-05-26PwC expands AI partnership with Anthropic, certifies 30,000 staff (peer context)
- 2026-05-18Pitcher Partners reports FY2025 revenue $355.93m, ranked 9th on AFR Top 100 (peer)
- 2025-11-26Pitcher Partners credits AI investment for AFR top-10 accounting firm ranking (peer)
- 2025-11-25BDO Australia reports FY2025 revenue $606.5m, up 12% YoY (peer)
- 2025-10-13William Buck Transparency Report 2025 discloses over $200m turnover, 150+ partners, 1,200+ staff
- 2019-06William Buck SA merges with Tregloans, forming ~170-strong Adelaide team
- 2017William Buck merges with SP Accountants
- 2014William Buck merges with Flood Allen
- 1895William Buck founded in Melbourne, Australia
Revision history
30 July 2026
First assessed. Hard to displace. The text above is fixed as of this date and is not edited afterwards.
In the same band
Sources
- William Buck Australia (2024-11-18)
- William Buck Transparency Report 2025 (2025-10-13)
- Accountants & Business Advisors Australia & New Zealand (2026-07-15)
- William Buck SA merges with Tregloans (2024-07-09)
- About New Zealand William Buck
- Accounting and Advisory Services (2026-07-15)
- Corporate Finance Services (2026-07-15)
- Accountants & Business Advisors Australia & New Zealand (2026-07-15)
- BDO ranks among top five accounting firms in AFR 2025 list (2025-11-25)
- The rise of accounting's second tier firms (2026-05-18)
- Letter (Kelly Partners ASX announcement)
- The Australian Financial Review (Top 100 Accounting Firms) (2025-11-25)