How Do Banks Dispute Charges and Investigate Claims

When you tell your bank a charge is wrong, it files a formal claim called a chargeback through the card network (Visa, Mastercard, or another) and runs an investigation under federal rules. Which rules apply, how fast the bank must act, and how much money you could lose all depend on one thing: whether the disputed transaction hit a credit card or a debit card. That split shapes everything about how banks dispute charges on your behalf, so the first step in any dispute is knowing which track you’re on.

Credit card disputes are governed by Regulation Z, which implements the Fair Credit Billing Act.¹ Debit card and other electronic fund transfer disputes fall under Regulation E.² Both give you 60 days to report, but almost nothing else about them lines up.

How to File the Dispute

For a credit card charge, your notice must be in writing and sent to the billing inquiry address printed on your statement. That address is not the payment address, and a phone call alone does not preserve your rights under Regulation Z.³ The FTC recommends sending the letter by certified mail with a return receipt so you have proof the issuer got it.

For a debit card charge, the bank must accept either oral or written notice.² A phone call is enough to trigger the bank’s legal obligations, though the bank can require written confirmation within 10 business days. Putting it in writing is a good idea either way.

Your notice should include your name, account number, the date the charge appeared, the exact amount, the merchant name as it shows on your statement, and why you believe the charge is wrong. Attach copies (never originals) of receipts, order confirmations, delivery tracking, screenshots, or any emails with the merchant. That evidence becomes the foundation of your bank’s case when it goes to the merchant’s payment processor.

Most banks let you open a dispute inside their app or online banking portal by selecting the transaction. A branch visit or a customer service call works too. Just remember the written-notice rule for credit cards: digital or phone contact gets things moving, but Regulation Z’s protections turn on a letter to the billing inquiry address.

Contact the Merchant First for Credit Card Purchase Disputes

If you’re disputing goods or services on a credit card (as opposed to outright fraud), federal law conditions your right to assert claims against the issuer on a good-faith attempt to resolve the problem with the merchant first.⁴ This requirement applies when the purchase exceeded $50 and happened in your home state or within 100 miles of your billing address. Documenting that attempt — a dated email, a chat transcript, a call log — keeps the issuer from denying the dispute on procedural grounds.

The 60-Day Deadline and What It Costs to Miss It

Both credit and debit disputes share the same clock: you must notify your bank within 60 days after the statement containing the disputed charge was sent to you.¹² The consequence of missing it differs sharply by card type.

On a debit card, the penalty is harsh. If unauthorized transfers appear on your statement and you don’t report within 60 days, you face unlimited liability for any unauthorized charges that occur after that 60-day period and before you finally notify the bank.⁵ A thief could drain the account, and the law gives you no right to recover those funds.

On a credit card, missing the 60-day window means losing the Fair Credit Billing Act’s dispute protections — the issuer can decline to investigate on timing alone. For unauthorized charges specifically, the Truth in Lending Act’s $50 liability cap does not carry the same 60-day limitation, so some protection remains even after the deadline passes.⁶

How Much You Could Owe on an Unauthorized Charge

Your maximum financial exposure for fraud depends entirely on the card.

Credit Cards

Federal law caps your liability for unauthorized credit card charges at $50, no matter how much the thief spent, provided the issuer gave you notice of your potential liability and a way to report the loss.⁶ Most major issuers advertise zero-liability policies that waive even that $50.

Debit Cards

Debit liability is tiered and rises fast:⁷

Report within 2 business days of learning about the activity, and your liability is capped at $50 or the amount taken before you notified the bank, whichever is less.
Report after 2 business days but within 60 days of the statement, and liability can reach $500 for unauthorized transfers that occurred after the two-day window.
Report more than 60 days after the statement, and you face unlimited liability for unauthorized transfers made after the 60-day period and before you notify the bank.

Because a debit card pulls directly from your bank account, acting within two business days of noticing anything suspicious is the single most important thing you can do.

How the Bank Investigates

Once the bank accepts the dispute, two things happen in parallel. The bank runs its customer-facing investigation under Regulation E or Z, and it sends a chargeback notification through the card network to the merchant’s payment processor (the acquirer), which alerts the merchant. That notification carries a reason code identifying the type of dispute — unauthorized transaction, merchandise not received, duplicate charge, and so on.⁸

The merchant then has a limited window, typically 20 to 45 days depending on the network, to respond with evidence defending the transaction, such as proof of delivery, a signed authorization, or usage records.⁸ If the merchant misses the deadline, the case resolves in your favor by default. If the merchant already refunded you, the bank closes the case.

Debit Card Timeline

The bank must investigate and reach a decision within 10 business days of receiving your notice. It then has three business days to report its findings and one business day to correct any confirmed error.²

If the bank can’t finish in 10 business days, it can take up to 45 days — but only if it provisionally credits your account for the full disputed amount (including any interest) within those first 10 business days.⁹ The bank must tell you the amount and date of the provisional credit within two business days of posting it, so you can use the funds while the investigation runs. Longer windows apply to new accounts (opened within the last 30 days), international transfers, and point-of-sale debit card transactions, where the bank gets up to 20 business days before provisional credit and up to 90 days to finish.²

Credit Card Timeline

The issuer must send written acknowledgment within 30 days of your billing error notice, unless it fully resolves the dispute in that period.¹ It then has two complete billing cycles, and in no event more than 90 days, to finish the investigation.

Regulation Z doesn’t require provisional credit. Instead, you don’t have to pay the disputed amount or related finance charges while the investigation is pending, the issuer can’t try to collect it, and it can’t report the amount as delinquent to the credit bureaus during this period.¹⁰¹¹

The Decision and Your Account

If the bank confirms the charge was wrong or unauthorized, any provisional credit on a debit account becomes permanent. On a credit card, the issuer removes the charge and any associated finance charges from your balance.

If the bank finds the charge was legitimate, it must send a written explanation of its reasoning. For debit disputes, that notice must tell you that you can request copies of the documents the bank relied on, and the bank reverses any provisional credit.¹² For credit card disputes, the issuer notifies you of what you owe and why, and you can request copies of supporting documents.³

If Your Dispute Is Denied

A denial is not necessarily the end. On a credit card, you can appeal in writing within the payment period the issuer gives you, or within 10 days of receiving the explanation, whichever is later, stating that you still dispute the charge and refuse to pay.³ The issuer can report the amount as disputed to the credit bureaus at that point, but it must also report that you disagree with the finding.

If you think the bank violated federal rules — missed a timeline, skipped the written explanation, failed to issue provisional credit when required — file a complaint with the Consumer Financial Protection Bureau at consumerfinance.gov/complaint or by calling (855) 411-2372. The CFPB forwards the complaint and generally gets a company response within 15 days.¹³ Include dates, amounts, and copies of your communications (up to 50 pages of supporting documents).

If the denial leads to negative information on a checking account consumer report like ChexSystems, you can dispute that record directly with the reporting company and, if the reinvestigation doesn’t fix it, file a brief statement of up to 100 words that must appear in future reports.¹⁴

1
eCFR. 12 CFR 1026.13 – Billing Error Resolution
2
eCFR. 12 CFR 1005.11 – Procedures for Resolving Errors
3
Federal Trade Commission. Using Credit Cards and Disputing Charges
4
eCFR. Part 226 Truth in Lending (Regulation Z)
5
Consumer Financial Protection Bureau. 1005.6 Liability of Consumer for Unauthorized Transfers
6
Office of the Law Revision Counsel. 15 U.S. Code 1643 – Liability of Holder of Credit Card
7
eCFR. 12 CFR 1005.6 – Liability of Consumer for Unauthorized Transfers
8
Mastercard. How Can Merchants Dispute Credit Card Chargebacks
9
Consumer Financial Protection Bureau. 1005.11 Procedures for Resolving Errors
10
Consumer Financial Protection Bureau. 1026.13 Billing Error Resolution
11
Federal Trade Commission. Fair Credit Billing Act
12
eCFR. 12 CFR 1005.11 – Procedures for Resolving Errors
13
Consumer Financial Protection Bureau. Submit a Complaint
14
Office of the Law Revision Counsel. 15 U.S. Code 1681i – Procedure in Case of Disputed Accuracy