What is a BCBS alpha prefix?

If you bill Blue Cross and Blue Shield patients, the first three characters of the member ID are the part of the card that routes the claim. Those three characters are the prefix, often called the alpha prefix. This guide explains what it is, why it matters for claims and eligibility checks, and when a card will not have one.

What the prefix is

The Blue Cross Blue Shield Association defines the alpha prefix as the three characters in front of the subscriber identification number on a Blue member ID card. It identifies the member's local Blue company or national account, so the claim can be routed correctly.

The plan manuals we cite say the same: the prefix identifies the member's Blue plan or national account. One describes it as three alpha or alphanumeric characters at the start of the member ID, and another calls it the main identifier for out-of-area members.

The prefix sits in the first three positions of the ID number. The characters after it can run from 6 to 14 numbers or letters, for an ID of up to 17 characters in total.

Why the prefix matters for billing

Under the BlueCard program, you can submit claims for patients from other Blue plans to your own local Blue plan. The prefix is what lets those claims be routed: one plan's manual describes it as critical for electronically routing specific HIPAA transactions to the right plan.

That is why the plan manuals we cite ask you to include the member's complete ID number, including the three-character prefix, when you submit a claim. Blue Cross Blue Shield of Massachusetts extends this to referrals to vendors, lab requests and prescriptions for prosthetics, orthotics and durable medical equipment.

The prefix also matters on the phone. When you call the BlueCard Eligibility line to check an out-of-area member's coverage, you are asked to give the member's prefix, and the line routes the inquiry to the member's plan.

Letters only, or letters and numbers?

Historically, every prefix was three letters, which is where the name "alpha prefix" comes from. Beginning in 2018, the Blue Cross Blue Shield Association started issuing alphanumeric prefixes because the supply of all-letter combinations was running low. Existing all-letter prefixes did not change. Alphanumeric prefixes are assigned for new products or new large national group accounts.

In practice, a digit in the first three characters can be correct. Enter what the card shows.

Cards without a prefix

Not every Blue card has a three-character prefix. One plan's ID card guide lists these exceptions:

• Stand-alone vision and pharmacy delivered through an intermediary model
• Stand-alone dental products
• The Federal Employee Program (FEP), where the ID starts with the letter "R"

FEP member IDs begin with "R" followed by 8 digits, in place of a three-character prefix, and FEP is excluded from the BlueCard program. For these cards, follow the instructions printed on the card to verify eligibility, submit claims and find plan contact details.

One plan's manual also notes that some members carry outdated cards that may not show a prefix. Ask for the current card.

Rules to follow

Each of these points comes from one of the plan manuals we cite:

• Do not make up a prefix. Submit claims only with valid prefixes.
• Do not guess a prefix or try to work one out from the patient's home plan. Enter the ID exactly as it appears on the card.
• If a card has no prefix, do not create one or copy one from another member's card, even a card from the same plan. Doing so can delay inquiries and claims.
• Claims with incorrect or missing prefixes or member ID numbers cannot be processed.

If a prefix is not in our data, see what to do when a prefix is not found.