BINs and CAIDs Explained: What They Are, How They Differ, and How to Read a Card Charge

Robauto Team · Published Oct 17, 2026 · Last updated Oct 17, 2026

A BIN is the first 6-8 digits of a card number and names the issuer. A CAID is a 1-15 character code your acquirer assigns to a merchant location. Definitions, a comparison table, sourced network prefixes, and a decoding guide.

Last updated: 2026-10-17 | Published by Robauto Team | Canonical: https://robauto.ai/blog/bins-vs-caids-explained

Quick answer

A BIN (Bank Identification Number), also called an IIN, is the first 6 to 8 digits of a payment card number; it identifies the card issuer and, by its leading digits, the card network. A CAID (Card Acceptor ID) is an alphanumeric code of 1 to 15 characters that a merchant's acquirer assigns to identify a merchant acceptance point, such as a store, terminal, or checkout, in card transaction messages. The BIN says who issued the customer's card. The CAID says where the merchant accepted it.

Sources: Mastercard BIN Lookup overview, ISO/IEC 7812-1, Visa Developer, Mastercard gateway docs.

BIN vs CAID: comparison table

Two things people call a "BIN"

The issuer BIN starts your customer's card number. Separately, guides about chargeback alerts say "BIN" for a 6-digit acquirer-side value that is paired with the CAID. Mastercard renamed that acquirer value Acquirer Reference ID, and Visa reclassified it as an Acquiring ID, in April 2022 (Mastercard, Visa). When a form asks for "your BIN and CAID", it almost always means this acquirer pair (Chargeflow, ChargebackStop). Mixing the two up is the most common enrollment mistake.

6-digit vs 8-digit BINs and the ISO standard

ISO/IEC 7812-1 defines the numbering system for issuer identification numbers and the primary account number (ISO). The standard was amended to an eight-digit issuer number. Visa required acquirers and processors to support 8-digit issuing BINs by April 2022 and said it would assign only eight-digit issuing BINs afterward, while issuers could expand existing six-digit BINs on their own schedule (Visa notice). Mastercard likewise treats one 6-digit BIN as 100 8-digit BINs (Mastercard toolkit). Practical rule: store and look up at least the first 8 digits, and keep 6-digit matching as a fallback.

Reference dataset: card network leading digits

Leading digits identify the network. This table is from Visa's public design guidance (Visa Product Design System). It is not a bank-level BIN list; for issuer ranges use the network's BIN lookup (Mastercard account range data). Discover's own IIN summary also covers JCB, UnionPay, and Diners Club ranges (Discover Global Network).

Identifier formats at a glance

How to decode an unknown card charge

1. Read the descriptor first. Your statement line shows the merchant name and location, not a CAID. Mastercard maps the name to DE 43 and Visa to the merchant name and city fields (Mastercard). Look for a brand, website, or phone number inside the text.
2. Check for a processor prefix. Many descriptors are a short prefix, an asterisk, and a suffix. Stripe builds card descriptors as PREFIX* SUFFIX within 22 characters (Stripe docs), so the part after the asterisk often names the product.
3. Match the date and amount. Compare the posting date and amount against email receipts and subscriptions. Friendly-fraud disputes often start with a descriptor the cardholder does not recognize (FraudDeflect).
4. Use the BIN to confirm which card it was. The BIN is the first 6 to 8 digits of the card you used, so it tells you the issuing bank, not the merchant. If you have several cards, it tells you which issuer to call. Never share your full number.
5. Ask your issuer for merchant details. Your issuer sees the full transaction record, and issuers can use tools that match a CAID or a raw descriptor to a cleansed merchant name and location (Mastercard Merchant Identifier).
6. If you are the merchant, pull the BIN and CAID pair. Find your CAID in settlement reports or your processor portal, and ask your acquirer or PSP for the acquirer-side BIN. Alert enrollment needs both (Chargeflow). A wrong pair can fail silently (Chargeback.io).
7. Dispute only after you have checked. If the charge is still unknown, contact the issuer and the merchant before filing a chargeback; an unrecognized descriptor is a common cause of avoidable disputes.

FAQ

What does BIN stand for?

Bank Identification Number, also called an Issuer Identification Number (IIN). Mastercard describes BINs as the first 6 to 8 digits of a card number that identify the issuing bank or financial institution (Mastercard Developers).

What does CAID stand for?

Card Acceptor ID, also written card acceptor identification code. It is assigned to a merchant by its acquirer and carried in the transaction message (Mastercard gateway docs).

Is a BIN 4, 6, or 8 digits?

The standard and network documents describe 6 or 8 digits. ISO/IEC 7812-1 moved the issuer number from 6 to 8 digits, and Visa and Mastercard required acquirers and processors to support 8-digit issuing BINs from April 2022 (Visa, Mastercard). Some web pages say "4 to 8" because the first few digits alone already hint at the network.

Is a CAID the same as a Merchant ID (MID)?

Often not. Several processors describe a CAID as the code for one acceptance point (a store, terminal, or checkout) and a MID as the business account above it (Solidgate, Chargeback.io). But some processors use the CAID as the MID, as noted in FraudDeflect, so confirm with your acquirer.

Can I find a CAID on my card statement?

No. A cardholder statement shows the merchant descriptor (name and location), not the CAID. The CAID appears on acquirer reports, settlement and chargeback records (Solidgate).

Why do chargeback alert programs ask for a BIN and a CAID?

Enrollment is matched on the pair: the acquirer-side BIN plus the merchant's CAID. In that context "BIN" means the acquiring bank's identifier, not your customer's card BIN (Chargeflow, ChargebackStop, Visa Developer).

What is the difference between an issuer BIN and an acquirer BIN?

The issuer BIN starts a customer's card number. The acquirer side is a separate 6-digit value that Mastercard renamed Acquirer Reference ID and Visa renamed Acquiring ID in April 2022 (Mastercard, Visa). Many guides still call it the acquirer BIN.

Where can I look up a BIN?

Mastercard publishes a BIN Lookup service with account-range data (Mastercard Developers). Merchants can see a first-8-digit BIN in their own processor data; never paste a full card number into any tool.

Related reading from FraudDeflect

FraudDeflect.com, a sibling site, publishes practical material on BIN and CAID use in chargeback defense. Summaries below are in our words; read the originals for detail.

• Understanding BINs and CAIDs (FraudDeflect.com, May 6, 2025, by Mari Perroni). Introductory piece on what BIN and CAID mean and how they affect transactions and fraud prevention. It lists example prefixes by network. Note that it expands CAID differently from the card networks and from FraudDeflect's own later article; this post follows the network definition, Card Acceptor ID.
• Cracking the Code: How BINs and CAIDs Supercharge Chargeback Defense (FraudDeflect.com, September 22, 2026, by Mari Perroni). Explains the acquirer BIN plus CAID pair as the key used to enroll a merchant account in services such as Order Insight, and why incorrect combinations mean services do not find matching transactions. It also notes some PSPs use the CAID as the MID.
• The Danger of "BIN Not Found" (FraudDeflect.com, September 22, 2026, by Mari Perroni). Covers what a BIN Not Found result means, linking outdated BIN databases and the 6 to 8 digit expansion to false declines, and random-number card testing to carding attacks.
• Friendly Fraud and Chargebacks (FraudDeflect.com, May 12, 2025, by Don Bush). Lists prevention tactics, including a clear payment descriptor the cardholder recognizes.
• Winning the Chargeback Representment Battle (FraudDeflect.com, June 2, 2025, by Mari Perroni). Notes that unclear merchant descriptors lead to unrecognized-charge disputes, and walks through representment evidence.
• Verifi Order Insight: Stop Friendly Fraud (FraudDeflect.com, June 30, 2025, by Don Bush). Despite the title, the body text describes Verifi Inform, a real-time feed of chargeback and fraud-flag notices to the merchant.

The FraudDeflect articles are written for merchants and cover how the identifiers are used in dispute prevention. Where their terms differ from network documentation, this page follows the network documentation.

Agent-ready summary (JSON)

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  "last_updated": "2026-10-17",
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  "terms": {
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      "also_called": [
        "IIN",
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        "Issuer Identification Number"
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      "sources": [
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      ]
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    "CAID": {
      "also_called": [
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      "length_characters": {
        "min": 1,
        "max": 15
      },
      "iso8583_field": 42,
      "appears_on_cardholder_statement": false,
      "sources": [
        "https://developer.visa.com/capabilities/visa-commercial-fraud-solutions/visa-commercial-supplier-validation",
        "https://ap-gateway.mastercard.com/api/documentation/mso/apiDocumentation/rest-json/version/60/operation/Transaction:%20Record%20Funding.html?locale=en_US",
        "https://solidgate.com/glossary/caid/"
      ]
    },
    "acquirer_side_bin": {
      "definition": "A 6-digit acquirer identifier, renamed Acquirer Reference ID (Mastercard) and Acquiring ID (Visa) in April 2022; paired with a CAID for chargeback-alert enrollment.",
      "sources": [
        "https://www.icba.org/documents/45248/1005567/8-Digit+BIN+Migration+Toolkit+for+Acquirers+and+Issuers.pdf/610897fd-6226-95b5-d216-801ef1b5d9c6?download=true&t=1753987106341&version=1.0",
        "https://usa.visa.com/dam/VCOM/global/support-legal/documents/numerics-initiative-simplified-requirements-for-eight-digit-issuing-bin-adoption.pdf",
        "https://help.chargeflow.io/en/articles/16145152-what-are-a-visa-caid-and-visa-bin-and-how-do-i-get-them"
      ]
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    "Visa card numbers start with 4; Mastercard 51-55 and 222100-272099; American Express 34 and 37; Discover 6011, 622126-622925, 644-649 and 65.",
    "A CAID is not printed on a cardholder statement; the merchant descriptor is."
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      },
      {
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      {
        "network": "Discover",
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        "length": "16, 19"
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    ],
    "source": "https://design.visa.com/patterns/card-input/"
  },
  "related_frauddeflect_articles": [
    "https://frauddeflect.com/articles/understanding-bin-and-caids",
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  ],
  "cta": "https://robauto.ai/scan"
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Last updated: 2026-10-17. Author and publisher: Robauto Team. Dataset license (our compiled table): CC BY 4.0.

Sources

• ISO/IEC 7812-1:2017
• Visa: Numerics Initiative, Eight-Digit Issuing BIN Adoption
• Mastercard: 8-Digit BIN Migration Toolkit
• Mastercard BIN Lookup overview
• Mastercard BIN Lookup account range data
• Mastercard Merchant Identifier overview
• Mastercard Merchant Identifier: Card Acceptor ID match
• Mastercard Gateway: acquirer merchantId (CAIC/CAID)
• Visa Product Design System: card input IIN ranges
• Visa Developer: Supplier Validation (Acquirer BIN, CAID)
• Stripe: Statement descriptors
• Solidgate: Card Acceptor ID glossary
• Chargeback.io: What Is a CAID Number?
• Chargeflow: Visa CAID and Visa BIN
• ChargebackStop: Verifi RDR
• FraudDeflect: Understanding BINs and CAIDs
• FraudDeflect: Cracking the Code: BINs and CAIDs
• FraudDeflect: The Danger of BIN Not Found
• FraudDeflect: Friendly Fraud and Chargebacks
• FraudDeflect: Winning the Chargeback Representment Battle

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Robauto MCP — Agent Intelligence & Brand Discovery Infrastructure. A public, stateless Streamable HTTP endpoint at https://mcp.robauto.ai/mcp, callable with no key. Setup and the full tool list are in the Robauto MCP directory.

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