Understanding Mastercard Chargeback Reason Code 4812: Account Number Not On File

Mastercard Reason Code 4812 (now merged into Mastercard Reason Code 4808) covers cases where the card number used in the transaction doesn't exist (is not a valid card number) or has expired. The issuer therefore refuses to accept liability for the transaction and pulls back the funds.

Key Takeaways

• What it means: The issuer doesn't recognise the card number. The transaction is therefore treated as unauthorised.
• Causes: Retired or fake account numbers. Forced transactions. Manual key-entry errors. Data corruption during processing.
• How to respond: Prove the account number used for the transaction is a valid one.
• How to prevent: Follow proper authorisation steps. Use EMV-compliant terminals. Handle soft declines with care.

What is a Mastercard Reason Code 4812 Chargeback?

Note: Reason Code 4812 has now been discontinued and is included under Reason Code 4808. However, the advice below is still relevant to Reason Code 4808 chargebacks relating to "Account Number Not On File".

Reason Code 4812 falls into Mastercard’s “No Authorisation” family. It appears when the issuer claims that the card number tied to a sale is “not on file”. In plain language, the bank believes the account never existed or was closed before the payment date. Because no valid account can be located, the issuer views the sale as unauthorised and reverses the funds.

While Mastercard has instructed issuers to use code 4808 for these cases, legacy systems or staff habits mean 4812 can still surface. When it does, merchants must recognise that the issuer is challenging the very existence of the card number, not the quality of goods or the satisfaction of the customer.

A disputed amount labelled 4812 usually reflects a breakdown in authorisation controls. Standard authorisation should reject a non-existent account immediately. The fact that the sale reached clearing suggests that something unusual – manual override, offline acceptance, or a glitch – let the payment proceed. For the merchant, the chargeback is a wake-up call: either the account was valid and you can prove it, or your system accepted bad data and you bear the loss.

Primary Causes for a Code 4812 Chargeback

Several scenarios can trigger an “Account Number Not On File” dispute. The most frequent cause is merchant error. A cashier may have keyed an incorrect digit, or staff may have forced a transaction after receiving a decline. In these cases, the acquirer sent an invalid Primary Account Number (PAN) to Mastercard, and the issuer now states it has no matching record.

Another origin point is retired or closed accounts. A subscription might bill an old card that the customer replaced months earlier. If authorisation was bypassed, perhaps because the transaction was processed offline, the payment goes through, only to be flagged later. Fraud also plays a role. Bad actors sometimes test randomly generated numbers or use fabricated PANs at online checkouts. If a merchant’s gateway does not verify the number in real time, a sale may sneak through. Once it reaches the bank, the missing account triggers a chargeback.

Technical faults round out the list. Data packets can corrupt during transmission, dropping or changing digits. Software bugs in point-of-sale or gateway code can mis-map card data fields. In rare cases, a cyber-attack inserts false numbers into the payment flow to mask larger fraud. Regardless of origin, all causes share a theme: the sale bypassed normal authorisation checks. Knowing this helps frame your response strategy, staff retraining, and system updates.

Time Limit for Disputing a Mastercard Reason Code 4812 Chargeback

Mastercard sets clear windows for every stage. The issuer must file the chargeback within 120 calendar days of the original transaction date or the date it learned of the issue. Once the acquirer receives the dispute, you, as the merchant, have 45 calendar days to respond. This 45-day clock is strict. Missing it concedes the case automatically.

During this period, you must decide to fight or accept. Gather records such as the authorisation log, terminal batch report, and the original receipt. If you choose to contest, submit your rebuttal and supporting evidence before the deadline. Provide concise explanations; long narratives rarely help and can confuse reviewers.

Remember that your acquirer may set an earlier internal cut-off to collect and review your documents. Contact your processor immediately after notice to confirm its timetable. Fast action keeps options open and can protect revenue that might otherwise be lost to administrative delay.

If you agree the claim is valid (perhaps the PAN truly never existed), accepting and adjusting internal processes is often the best course. Paying a small chargeback fee is cheaper than spending staff hours on a hopeless case. The time limit exists to keep the scheme running smoothly, so respect the calendar and plan early.

What 4812 Means for Consumers & Issuers

For consumers, a 4812 dispute may be raised when a statement shows a charge they do not recognise, perhaps against a closed account or expired card. By filing the dispute, the customer seeks quick relief and expects the bank to correct the error. However, this code generally refers to transactions against non-existent accounts, in which case there is no consumer involvement. 

Issuers view 4812 as a clear-cut liability shift. Because they have no record of the PAN, they regard the transaction as unapproved. From a risk standpoint, issuers also use these disputes to detect broader fraud patterns. A spike in 4812 cases tied to one merchant may signal system flaws that could expose the network to higher losses. The issuer may route these alerts to Mastercard or the acquiring bank for follow-up.

What 4812 Means for Merchants

When you receive a 4812 chargeback, the message is blunt: your payment flow accepted an account number the issuer cannot find. The immediate result is lost revenue, a chargeback fee, and elevated risk ratios. If your ratios rise above network thresholds, you may face higher processing costs or even account termination.

Operationally, you must trace how the invalid PAN entered your system. Check whether staff bypassed a decline, if the terminal was in offline mode, or if your e-commerce gateway skipped validation. Pinpoint the gap and fix it quickly. Each unresolved weakness can lead to more disputes and compound fees.

Finally, consider your relationship with the acquirer. High chargeback levels force banks to hold back reserves or demand rolling security deposits. Proactive remediation after a 4812 dispute shows the acquirer you are acting responsibly. That cooperation helps protect revenue by keeping processing terms favourable.

How to Respond to a Code 4812 Chargeback

Start by checking whether the account number on your receipt matches a legitimate Mastercard BIN and PAN. Use your processor’s lookup tools or contact the acquirer. If the number is wrong or incomplete, accepting liability is the sensible route. If the account is valid, locate the authorisation code. Provide a copy of the approval response that includes the code and date, formatted MMDDYY. Attach batch settlement reports showing the same PAN and approval code. This proves that the issuer, or Mastercard on the issuer’s behalf, did approve the transaction.

In addition, confirm that you submitted the sale within seven calendar days of authorisation. Late presentments can void the approval. Provide the settlement date to demonstrate timely submission. Compile your rebuttal into a brief cover letter. Reference Mastercard rules that the issuer must follow, such as the 120-day filing limit. Avoid emotional language and stick to facts. Submit the packet through your acquirer before the 45-day limit. A clear, well-supported case gives you the best chance to win and protect revenue.

Proactive Prevention: The Ultimate Defence

The best defence is to stop bad transactions before they settle. Keep all payment devices EMV-compliant, use address and CVV checks online, and never force a sale after a decline. Adopt automatic card-number validation in your gateway to catch typos and fake numbers instantly. Train staff to treat soft declines as warnings, not hurdles to clear.

To receive an early warning shortly after a chargeback has been raised, try out chargeback alerts. This service gives you the best chance of responding to (and possibly overturning) the chargeback within the allocated deadline.

‍