What Is Account Validation and CDV Checking?
Account validation is the process of checking a customer's bank account details before you try to collect against them. A debit order submitted against a mistyped account number is guaranteed to fail, and every avoidable failure costs a return fee, a delayed collection and a customer service conversation.
Two levels of validation are used in South African collections: check digit verification (CDV), which checks that account details are structurally valid, and account verification services (AVS), which check the account against the bank's actual records.
What is check digit verification (CDV)?
CDV is a mathematical check of the branch code and account number combination. Each South African bank publishes rules describing which account number patterns are valid for which branch codes, including a check digit calculation — an algorithm that detects typing errors such as a swapped or mistyped digit.
A CDV check answers one question: could this account number exist at this bank and branch? It runs instantly, offline, and costs nothing per lookup, which makes it the natural first line of defence at the point of capture — in a signup form, a call-centre screen or a bulk file import.
What CDV cannot tell you:
- whether the account actually exists,
- whether it is open or closed,
- whether it belongs to your customer,
- whether it accepts debit orders.
An account number can pass CDV perfectly and still belong to nobody.
What is real-time account verification (AVS-R)?
Account verification services close the gap CDV leaves. A real-time AVS request (AVS-R) is sent to the customer's bank, which checks the supplied details against its records and responds within seconds. Depending on the bank, an AVS-R result can confirm:
- the account exists and is open,
- the account accepts debit orders,
- the account holder's ID number or registration number matches the supplied details,
- the initials and surname match,
- how long the account has been open.
Because AVS-R confirms the account against live bank data, it also acts as a fraud control: it catches customers who supply someone else's account details, whether by mistake or deliberately.
How do CDV and AVS-R fit together?
| CDV | AVS-R | |
|---|---|---|
| What it checks | Branch/account number structure | The account at the bank |
| Confirms account exists and is open | No | Yes |
| Confirms ID/name match | No | Yes |
| Speed | Instant, offline | Real time, seconds |
| Cost per check | None | Per-lookup fee |
| Best used | At capture, on every entry | Before first collection or mandate registration |
The practical pattern is: run CDV on every account number as it is captured, then run AVS-R once the details pass CDV — before the mandate is registered and the first collection is submitted.
Why does validation reduce unpaids?
A meaningful share of debit order failures have nothing to do with the customer's willingness or ability to pay — they fail because the account details were wrong from the start: no such account, account closed, or an account that does not accept debits. These failures are entirely preventable.
Validating before submission means:
- fewer unpaids and lower return fees,
- the first collection succeeds, which sets the tone for the whole payment relationship,
- DebiCheck mandate registrations do not fail on bad account details,
- fraud using third-party account numbers is caught at onboarding rather than at dispute stage.
Kwik runs CDV and real-time account verification as part of its debit order onboarding flow, so collections are only ever submitted against accounts that exist, are open and belong to the customer.
Related topics
Action Dates and Cycles
How debit order action dates, submission cut-offs, banking and non-banking days and date adjustment rules determine when your collections run.
Unpaids and Returns
Common EFT debit order unpaid and return reason codes, including insufficient funds, closed accounts and stopped payments, and when you may resubmit.