When a platform holds money that belongs to someone else, whether that is a marketplace holding seller proceeds or a payments business holding customer balances, UK regulation requires that money to be protected if the firm fails. There are two distinct regulatory routes to that protection, and they are not interchangeable. E-money safeguarding and client money accounts under the FCA's Client Assets Sourcebook (CASS) rest on different legal foundations, apply to different types of firm, and produce different outcomes for the customer if things go wrong. Product and finance teams building on fintech banking infrastructure need to know which regime applies to their business model before they design account structures around it.

Two different legal starting points

E-money safeguarding applies to authorised electronic money institutions (EMIs) and their agents, under the Electronic Money Regulations 2011. When a customer's funds are exchanged for electronic money, the EMI must protect that value, either by holding it separately from its own operational funds or by covering it with an insurance policy or comparable guarantee. The legal mechanism is safeguarding, not trust.

Client money accounts under CASS apply to firms conducting regulated payment or investment activity where money is held on trust for the client rather than exchanged for e-money. This is the older, more established regime, built primarily for investment firms and payment institutions carrying out payment services without issuing e-money. Under CASS, the firm holds the money as trustee, and the client retains a proprietary interest in it. That distinction, e-money issuance versus trust-based client money, determines which rulebook applies.

How the mechanics differ in practice

Under e-money safeguarding, the EMI typically places customer funds in a designated account at a bank, separate from its own funds, and performs a reconciliation exercise, usually daily, to confirm the amount safeguarded matches what customers are owed. If the EMI becomes insolvent, safeguarded funds are meant to be returned to customers ahead of general creditors, following an insolvency practitioner's distribution process.

Under CASS, the firm holds money in one or more client money accounts, again segregated from firm funds, but the legal relationship is a trust. This means client money is, in principle, protected from the firm's creditors from the moment it is received, not just from the moment it is deposited into a segregated account. CASS also imposes its own reconciliation discipline, commonly referred to as the internal and external client money reconciliation, run at a similarly high frequency, along with detailed record-keeping obligations under the FCA's rulebook.

Both regimes share a common purpose, keeping customer money out of the firm's own balance sheet risk, but they diverge in legal form, in the paperwork the firm must maintain, and in how an insolvency practitioner would approach distribution.

Which model applies to which business

The model that applies is not a choice the platform makes freely; it follows from the regulatory permission the underlying institution holds. A platform issuing e-money wallets, EUR IBAN issuance for European customers, or GBP collection accounts with a sort code and account number for UK customers, is typically operating under an EMI's e-money safeguarding regime. A platform relying on a payment institution that executes payment services without issuing e-money, moving funds through client money accounts instead, sits under CASS.

This matters for marketplace payouts in particular. A marketplace collecting funds from buyers and paying out to sellers needs to know, precisely, whether those held balances are safeguarded e-money or CASS client money, because the answer determines what disclosures are required, how quickly funds must be passed on, and what happens to seller balances if the underlying provider fails. It also affects how payment scheme membership is structured upstream, since scheme access, whether direct or via an aggregator, sits behind whichever segregation model applies.

Operational implications for platform teams

For a platform building on an API banking platform, the choice of underlying model shapes several practical decisions:

  • Account structure. E-money safeguarding often uses pooled safeguarding accounts with a ledger tracking individual entitlements, while CASS structures may require more granular client money account segregation depending on the firm's permissions.
  • Reconciliation cadence and evidence. Both regimes demand frequent reconciliation, but the records a firm must produce to demonstrate compliance differ in format and retention period.
  • Cross-border flows. A platform settling cross-border payments SWIFT alongside domestic rails needs clarity on whether funds in transit are still considered safeguarded or client money at each stage, since the answer affects how quickly a failure would expose customers to loss.
  • Disclosure to end customers. Terms and conditions should describe accurately which protection applies, since e-money safeguarding and CASS trust protection carry different practical consequences and different regulatory wording requirements.

What this means when evaluating a BaaS provider

A BaaS provider offering embedded account infrastructure, EUR IBAN issuance, GBP collection accounts, or multi-currency payout rails, will typically operate under one of these two models, or in some cases under a combination if it holds multiple permissions across jurisdictions. Platform teams should ask, plainly, which regime protects the funds sitting in their customer accounts, how the safeguarding or client money reconciliation is evidenced, and what the insolvency waterfall would actually look like for their customers if the provider or its underlying bank failed. These are not abstract questions. They determine what a platform can honestly tell its own users about the safety of their money.

The practical takeaway

E-money safeguarding and CASS client money accounts both exist to keep customer funds separate from a firm's own risk, but they are built on different legal foundations and produce different outcomes in a failure scenario. Understanding which regime governs a given flow of funds, whether it touches sort code and account number rails domestically or moves across borders through correspondent banking, is a basic requirement for anyone designing or evaluating fintech banking infrastructure, not a detail to leave to the legal team alone.