Credentialing problems announce themselves in February. That is when the denials for "provider not eligible on date of service" and "provider not in network" from January visits arrive, and by then a month of claims is affected. The cause is almost always something that could have been checked in December: a plan that entered the market and never received an application, a revalidation notice that went to an old address, a CAQH attestation that expired over the holidays.
This January is busier than most. Medicare Advantage carriers terminated plans in hundreds of counties for 2026 and launched new products in others. Marketplace patients are switching carriers as the enhanced premium tax credits expire. Insurers have committed to honoring prior authorizations across plan changes for 90 days from January 1. And most practices have at least one new provider starting in the first quarter. Here is the list we work through in the last days of December and the first days of January.
Key takeaways
- Start with the plans your patients will actually have in January, taken from December eligibility responses, and compare them to the plans you are contracted with. The gaps are the work.
- Refresh the provider-payer grid: effective dates, payer identifiers and the next revalidation or recredentialing date for every cell. Anything due in the first quarter is worked now.
- CAQH attestations expire every 120 days. One that lapses between December 20 and January 5 will stop any application a payer touches in that window.
- A new provider hired in November for a January start is already late for most commercial plans. Submit Medicare first, then the two or three plans that carry most of your revenue, and schedule around the rest.
1. Network status with every plan your patients will have in January
Start with the plans, not the providers. Pull the list of plans your patients are enrolled in for 2026 from your eligibility responses in December; the 271 response usually carries the plan name and product. Compare it to the list of plans your group is contracted and credentialed with. The gaps fall into three groups:
| Situation | What it looks like | What to do |
|---|---|---|
| New MA product from a carrier you already contract with | Same carrier, new plan name, new product type (HMO instead of PPO) | Confirm in writing that your existing contract covers the new product. It often does not for narrow-network products. |
| New carrier in your market | Plan name you have never billed | Request a contract now. Credentialing takes 60 to 120 days; the patient will be out of network until it completes. |
| Terminated plan | Plan that ends December 31 | Note which patients were on it and confirm where they moved; nothing to credential, but the referral and authorization rules change. |
Patients on terminated MA plans who did nothing revert to Original Medicare on January 1, and they may pick a new MA plan during the January to March open enrollment period. Expect the same patient to change payer twice in the first quarter, and expect the second change to be the one nobody catches.
2. Every provider, every payer: effective and revalidation dates
Build or refresh the grid: providers down the side, payers across the top, and in each cell the effective date, the provider identifier the payer assigned, and the next revalidation or recredentialing date. Medicare revalidates every five years (every three for DMEPOS suppliers) and the due dates are in PECOS and on the CMS revalidation lookup; commercial plans typically recredential every three years; state Medicaid programs vary. Anything due in the first quarter of 2026 is worked now. A missed Medicare revalidation deactivates billing privileges, and reactivation does not always restore the gap.
The grid also answers the February denial before it arrives. When a claim comes back "provider not eligible on date of service", the first question is whether the effective date in the grid matches the payer's record. Half the time the payer loaded the wrong date, and the approval letter in your file wins the argument. The other half, the grid was wrong and the claims were billed too early. Either way, you cannot tell without the grid.
3. CAQH attestation over the holidays
CAQH ProView requires re-attestation every 120 days. An attestation that expires between December 20 and January 5 will expire while everyone is out, and any payer that pulls the profile in that window will stop the application. Check every provider's next attestation date today. If it falls in the holiday window, attest early. Upload any document expiring in the first quarter, especially malpractice face sheets that renew on January 1 and DEA registrations, and confirm that every payer you are applying to is authorized to view the profile.
4. New providers starting in the first quarter
A provider starting on January 12 who was hired in November is already late for most commercial payers. Prioritize by revenue: Medicare first (PECOS applications submitted now can carry an effective date up to 30 days before the date the MAC receives the application, so submit before the start date), then the two or three commercial plans that represent most of the practice's revenue, then the rest. Schedule the new provider's first weeks with patients on plans where enrollment is effective, and hold claims for pending plans rather than billing them under another provider.
| Payer | Application submitted | Typical processing | Likely effective date | Scheduling rule until then |
|---|---|---|---|---|
| Medicare (PECOS) | December 1 | 30 to 60 days | Retroactive to the later of the start date or 30 days before receipt | See Medicare patients from day one; hold claims until approval |
| Largest commercial plan | December 1 | 60 to 90 days | Late February to early March; some plans backdate to the application date, most do not | Schedule with an enrolled provider or hold claims |
| State Medicaid | December 1 | 30 to 120 days by state | Varies; several states backdate to the application date | Check the state's retroactive rule before scheduling |
| Medicare Advantage plans | After the commercial contract or via delegated credentialing | 60 to 120 days | March or later | Route MA patients to enrolled providers |
| Remaining commercial plans | Rolling | 90 to 120 days | Second quarter | Hold or reschedule |
The table is why the offer letter should carry a credentialing start clause. A provider who signs in August and supplies documents in September is in network with the major plans by January. One who signs in November is not, and the practice eats the difference or the provider sees a thin schedule for two months.
5. Contract dates, rate exhibits and the authorization hand-off
Contract dates and rate exhibits. Many commercial contracts renew or reprice on January 1. Pull every contract and note the renewal date, the notice period and whether the 2026 rate exhibit has arrived. A contract tied to a percentage of the Medicare fee schedule will pay differently in January because the CY2026 conversion factor and RVUs changed; a contract with a fixed schedule should have a new exhibit. If the payer has not sent one, ask in writing before December 31 so the request is dated in the old contract year.
The prior authorization hand-off. From January 1, 2026, the insurers that signed the June 2025 commitments have said they will honor a prior authorization from a patient's previous plan for a 90-day transition when the patient changes plans mid-treatment. This is a credentialing team question as much as an authorization team question, because the new plan will ask whether the rendering provider is in network. Make sure the provider grid and the authorization log can be read together: patient, old plan, authorization number and dates, new plan, provider network status with the new plan.
The schedule from here
- This week (December 22): Pull the 2026 plan list from eligibility responses. Compare to contracted plans. Send contract requests for gaps. Check all CAQH attestation dates and attest early for anyone in the holiday window. Request missing 2026 rate exhibits before December 31.
- Week of December 29: Refresh the provider-payer grid. Work all first-quarter revalidations. Submit PECOS applications for first-quarter starts if they are not already in. Confirm new-product coverage under existing contracts in writing.
- Week of January 5: Load confirmed effective dates and identifiers into the billing system so claims are not held for enrolled providers. Re-verify eligibility for every Medicare and marketplace patient on the schedule. Set the claim hold for new providers by payer.
- Week of January 12: Read the first week of January remittances for eligibility and network denials, and reconcile them against the grid before they become a February pattern.
Questions we hear
A carrier says our contract covers all its products. Do we need anything in writing?
Yes. Narrow-network MA and marketplace products are frequently excluded from base contracts, and a verbal assurance does not survive a denial. Ask for the product list as an exhibit or an email from the provider relations representative, and file it with the contract.
Can a new provider see patients while credentialing is pending?
They can see patients; the question is who can be billed. Patients on plans where the provider is effective can be billed normally. For others, either hold the claims until the effective date (many commercial plans do not backdate) or schedule those patients with an enrolled provider. Billing under another provider's number outside the payer's own incident-to or locum tenens rules is a compliance problem, not a workaround.
How long should we keep credentialing records?
Keep every application, submission confirmation, approval letter and effective date for as long as the provider is with the practice and for the retention period your counsel advises afterward. When a payer disputes an effective date two years later, the submission confirmation is the evidence. Our credentialing and provider enrollment service keeps the grid, the dates and the reference numbers in the client dashboard, and the standard per-application rates are on the pricing page.
What to do this week
- Pull the January plan list from December eligibility responses and compare it to your contracted plans.
- Check every provider's CAQH attestation date and attest early for anyone expiring before January 5.
- Refresh the provider-payer grid and flag every revalidation or recredentialing due in the first quarter.
- Submit or confirm PECOS applications for every first-quarter start, and set the scheduling rule for each pending payer.
- Request missing 2026 rate exhibits and new-product confirmations in writing, dated before December 31.
