M3S

BCBS Prefix M3S

Blue Cross and Blue Shield of Illinois

Illinois • POS, HMO, Medicare Advantage

Billing essentials

Provider phone
(877) 860-2837
Electronic payer ID
00621
Claims mailing address
P.O. Box 650712 Dallas, TX 75265-0712
Timely filing limit
180 daysCompare all plans
Prior authorization phone
(800) 654-7385

Coverage under prefix M3S

POS

This is a Point of Service (POS) prefix. POS plans offer flexibility similar to a PPO but incentivize in-network care through lower cost-sharing. Members designate a primary care physician who can issue referrals for the highest level of benefits. Out-of-network claims are covered but at significantly reduced rates.

HMO

HMO coverage means this member must use providers within the plan's network. A primary care physician serves as the care coordinator and must authorize specialist referrals. Emergency services are the primary exception to the network requirement. Always verify referral status before providing non-emergency specialty care.

Medicare Advantage

This prefix is associated with Medicare Advantage. MA plans combine hospital (Part A) and medical (Part B) coverage, and many include prescription drug coverage (Part D). When billing, confirm whether the plan uses the same payer ID for MA claims as for commercial claims, as many BCBS companies use separate IDs.

About Blue Cross and Blue Shield of Illinois

State's only statewide customer-owned health insurer and independent licensee of the Blue Cross Blue Shield Association. Serves Illinois with commercial, Medicare, Medicaid and other plans.