Medicare Can Shut Off Your Eligibility Checks on December 1. The Cause Is an Email Address.

Most practices never think about how a Medicare eligibility check reaches CMS. The front desk clicks a button in the practice management system, a clearinghouse sends a 270 request, and Medicare's HIPAA Eligibility Transaction System (HETS) sends back a 271 response. That chain is about to depend on something small: whether the email address on your HETS enrollment still works.

In its October 8, 2026 MLN Connects newsletter, CMS told providers to confirm the email address on their HETS EDI enrollment by December 1, 2026. Its HETS release notes for this cycle, dated September 24, set out what happens if they don't.

What changes on December 1

HETS sends a monthly email on the first of each month that summarizes the prior month's eligibility activity for each enrolled NPI. Until now, when that email bounced, the MCARE Help Desk contacted the clearinghouse on file. From December 1, the rule is stricter:

• If delivery fails for three months in a row (October 1, November 1 and December 1, 2026), HETS suspends the enrollment record for that NPI.
• While it's suspended, HETS rejects every eligibility request a clearinghouse sends for that NPI, returning error code 97 in the 271 response, until the email is corrected.
• Only the provider or supplier can update the email address, and only through its Medicare Administrative Contractor (MAC). Your vendor, billing company, EHR or clearinghouse can't make the change for you.

The October 1 email has already gone out. If it bounced, one of the three months is already used. That's why this belongs on this month's task list, not December's.

Why it costs money, not just time

A rejected eligibility check doesn't stop a patient from walking in. It stops the front desk from confirming Medicare Part B coverage, Medicare Advantage enrollment, secondary coverage or preventive-service eligibility before the visit. Staff fall back to the MAC portal or the phone, one patient at a time, and some visits go ahead unchecked. The cost shows up weeks later as eligibility and coordination-of-benefits denials, and the timing is poor: January is when patients change plans and deductibles reset.

This isn't the first HETS tightening this year. Since May 11, 2026, HETS has required a valid HETS EDI enrollment on file for every NPI submitted for eligibility checks. Practices that went through that step in the spring should check which email address they used. It's often a person who has since left, or an inbox nobody reads.

A 15-minute check for this month

This is general information, not legal or compliance advice. The steps below follow CMS's notice:

• List every NPI your practice sends Medicare eligibility checks for: the group NPI and each rendering provider's, if your system checks under individual NPIs.
• Find out which email address is on each HETS EDI enrollment. Your MAC's EDI enrollment team or portal can confirm it.
• Use a shared inbox that more than one person reads, not one employee's personal work address.
• Ask whoever checks that inbox whether the October 1 HETS monthly email arrived. If it didn't, treat it as a warning.
• Ask your clearinghouse whether it has sent you any HETS email-failure notice.
• If an address is wrong, update it through your MAC before November 1, so the November email is delivered.
• Read the monthly report once it arrives. CMS says it lists eligibility activity for each NPI, so it also shows checks you didn't expect.

If a suspension does happen, the MAC's secure provider portal still checks eligibility while the email is being corrected.

Small settings, real denials

Many eligibility denials start with a setting nobody owns: an expired enrollment, an old email, a vendor link that was never updated. VOSKPO helps practices keep these front-end checks on the same calendar as their claims work. A revenue review can show where eligibility gaps are turning into denials.