What is Customer Due Diligence (CDD) for UK accountants?
Mehmood Rajoka9 min readUpdated May 2026
In brief: CDD (Customer Due Diligence) is the full process of verifying who a client is, understanding the business relationship, assessing their risk, and monitoring the relationship over time — required for all clients under The Money Laundering Regulations 2017.
Key points
- Standard CDD applies to most clients
- Simplified CDD is permitted for low-risk clients
- Enhanced Due Diligence (EDD) is required for high-risk clients and PEPs
- Ongoing monitoring is part of CDD — not a one-time check
- Evidence must be retained for five years after the relationship ends
The three levels of CDD — Standard, Simplified, and Enhanced — and when each applies under MLR 2017.