Professional codes of conductConfidentiality, record-keeping, and engagement-letter expectations under your local body (AICPA in the US, ICAEW / ACCA in the UK, CPA Australia / Chartered Accountants ANZ / TPB in Australia, and equivalents).
Data protection & tax-ID handlingGDPR (EU/UK), CCPA (California), Australia's Privacy Act and TFN Rule, and equivalents — strict rules on storing tax IDs and other sensitive personal information.
AML / KYC obligationsAccountants and consultants providing designated services (trust/company formation, asset transfers, managing client money) are reporting entities under FATF, US BSA, EU 5AMLD/6AMLD, UK MLR 2017, and Australia's AUSTRAC AML/CTF rules.