Mastercard 2-Series BINsThe Official Range, What the Fines Were & How to Test Your Checkout

Everything You Need to Know About Mastercard 2-Series Cards

For most of Mastercard’s history, a Mastercard card number always began with “5.” Every checkout form, terminal, and fraud rule written before 2017 could rely on that. And a great many of them did.

That rule stopped holding in 2017, when Mastercard began issuing cards with card numbers that began with 2. There are now a lot of those Mastercard 2-series card in circulation.

In this post, we will set out the official 2-series range, what the acceptance fines were and who was actually charged, where these cards still fail, and how to test that your own checkout accepts them.

What Is the Mastercard 2-Series BIN Range?

A bank identification number (BIN) is the first eight digits of a card number. BIN numbers used to be six digits in length before card networks adopted the extended ISO/IEC 7812-1 numbering standard in April 2022.

The first digit of the BIN on its own is the major industry identifier. 4 and 5 were traditionally reserved for banking and finance, while 2 was originally assigned to airlines. However, that class saw comparatively little use; so little, in fact, that Mastercard was allowed to repurpose a range of numbers within it.

The Mastercard 2-series BIN range is 222100 to 272099. Every card number issued with a number in that range is Mastercard-branded. It was authorized, cleared, and disputed under the same Mastercard rules as a card beginning 51 to 55.

Which digits a checkout has to read on a Mastercard number Two Mastercard numbers. 5555 5555 5555 4444 begins 55, in the 51 to 55 range. 2223 0031 2200 3222 begins 2223, in the 2221 to 2720 range added in 2017. Both are valid Mastercards. A checkout that only checks for the first range turns away the second.

5555 5555 5555 4444

Mastercard

Mastercard numbers begin 51 to 55.

2223 0031 2200 3222

Mastercard

Since 2017, Mastercard numbers also begin 2221 to 2720.

A checkout that only checks for the top row turns away the bottom row.

In practice this means 2-series acceptance has been a condition of accepting Mastercard for almost a decade. Not all systems are equipped to handle 2-series BIN cards, however, because numbers starting with 2 were not historically widely used, and a system nobody has updated will not have updated itself.

Where Can 2-Series Cards Still Fail?

Nearly a decade later, most terminals can accept 2-series cards with no problem. But, there’s still the potential for errors.

Online sellers have multiple points of vulnerability, including:

• Web Apps
• Shopping Cart & Checkout Software
• Payment Gateways
• Proprietary Systems
• Internal or External Loyalty Programs
• Data Analytics
• Fraud Prevention

Check with your acquirer to ensure you’re covered, then contact your vendor for any of the above services that apply. Ensure that they can accept and process Mastercard 2-series cards, or whether they will require a plugin to do so. Mastercard’s checklist also names dispute resolution systems, data warehouses, and staff training as areas to verify.

The most common point of failure in an eCommerce stack is also the simplest one: a card-number check on the checkout form — or in the payment gateway plugin behind it — that is still set to recognize only Mastercard numbers beginning in the 51 to 55 range. The card never reaches the acquirer, so no decline code is returned, and no report records the lost sale.

How to Verify Your Checkout Accepts 2-Series Cards

The verification process is short, and it can be handed to a developer or run by whoever owns checkout.

It has four parts; the order of operations matters, though, because the first part cannot catch a failure in the second.

Testing 2-series acceptance

Only the Live Test Covers the Whole Path.

A card number passes through several systems on its way to your acquirer. Each of the four tests looks at a different part of that path.

The path a card number takes

2223

1. Checkout form Card-number field
2. Gateway plugin Behind the form
3. BIN rules Fraud, loyalty, reporting
4. Processor Sandbox or live
5. Acquirer Your merchant bank

What each test checks

• Checked
• Not checked

1. 1Run a Test PaymentIn the processor’s sandbox
   Checks the processor only.
2. 2Validate the Card Number on the Checkout FormBefore the number is sent anywhere
   Checks the checkout form and gateway plugin.
3. 3Review Every Rule That Reads the BINFraud rules, BIN tables, loyalty and reporting
   Checks the BIN rules.
4. 4Run a Live 2-Series TransactionThe real test, end to end
   Checks the whole path, from the checkout form to the acquirer.

What Happens if a Transaction Fails Due to Inability to Accept 2-Series Cards?

When Mastercard began field testing merchant acceptance on June 30, 2017, any location that could not process a 2-series card exposed its acquirer to a noncompliance assessment.

A location that was identified as being unable to accept a 2-series card received a cure period. They could avoid an assessment by successfully processing one 2-series transaction from that location. If they didn’t cure the problem, then an assessment was levied on the acquirer, who could then pass it to the merchant (if allowed under the merchant agreement).

These penalties increased based on the number of days passed after deadline:

As of 2026, though, the field testing program is long finished. Now, the consequence of rejecting a 2-series card is commercial rather than regulatory: it just registers as another declined sale on a valid card. Neither Mastercard, nor the acquirer, will report the reason for the decline to you.

In practical terms, this means the cardholder sees “invalid card number,” and then leaves to go spend their money elsewhere. Mastercard will not assess you for it, and your acquirer will not report it. The sale is simply lost because of a rule that was implemented a decade ago.