The short answer
Sometimes, and it depends on the payer. Medicare can pay for services up to 30 days before your effective date, which is usually the day it received your application. That only applies if circumstances kept you from enrolling sooner, and only for services after you met every program requirement, including state licensure (42 CFR 424.520(d), 424.521).
Medicaid backdating is set by each state. Many commercial plans pay only from the effective date in a signed contract. Billing a new provider's visits under a colleague's NPI is not an option. Hold the claims, track each one's filing deadline, and start applications months before the first visit.
Payer by payer: the earliest date you can bill
The table shows the earliest date each type of payer pays from, and the condition attached. Read the conditions column first. That is where most practices lose money.
| Payer | Earliest billable date | Conditions | Source |
|---|---|---|---|
| Medicare | The later of the date your approved application was filed or the date you first saw patients at the location. Billing can reach back up to 30 days before that, or 90 days after a Presidentially declared disaster. | Only if circumstances prevented enrolling in advance, and only for services after you met every program requirement, including state licensure, at the enrolled location. | 42 CFR 424.520(d), 424.521(a) |
| Medicaid, Colorado | In most cases, enrollment can be backdated up to 365 days from the approval date. | Continuously licensed and meeting all enrollment criteria. The backdate approval letter works as the timely filing waiver. HCPF's backdating page says 10 months, so ask early. | HCPF timely filing FAQ |
| Medicaid, Texas | The enrollment effective date in your welcome letter. | Claims are rejected until enrollment is complete, then due within 95 days of completion and within 365 days of the date of service. | TMPPM Vol. 1, §6.1.4.2 |
| Medicaid managed care | After state Medicaid enrollment, then the plan's own credentialing. | Minnesota has required in-network managed care providers to enroll with the state Medicaid program since July 17, 2023. | MHCP Provider Manual |
| Medicare Advantage | Set by each plan, which credentials its own network. | CMS no longer requires clinicians to enroll in Medicare to join an MA network, but a plan can require it in its contract. No plan may pay a clinician who opted out of Medicare or is on CMS's Preclusion List. | 42 CFR 422.204, 422.220, 422.222; CMS Preclusion List FAQ |
| Commercial | Usually the effective date in the executed contract. | Some plans backdate and many don't. Ask each plan in writing before you hold a single claim. | Your contract with each plan |
Planning guide, not a legal opinion. Payers change their rules; confirm with each one.
Here is how the Medicare rule plays out. A physician starts seeing patients on March 1. The application is filed on May 1 and approved in June. The effective date is May 1, so billing can reach back to April 1 if the conditions are met. The March visits are not payable.
Can I bill Medicare before my effective date?
Only for up to 30 days, or 90 after a Presidentially declared disaster, and only if circumstances kept you from enrolling in advance. The services also have to come after you met every Medicare requirement, including state licensure, at the enrolled practice location. Your effective date is the later of the day your approved application was filed and the day you first saw patients at that location.
For a Medicare Advantage plan you have no contract with, here is how Medicare Advantage pays out-of-network. Ask the plan in writing how it handles a provider whose Medicare enrollment is still pending.
- Colorado: Colorado's Medicaid rules, including proof of timely filing.
- Texas: Texas's 95-day rules for Medicaid and state-regulated plans.
- Minnesota: Minnesota's managed care rules, including enrollment checks.
The "workaround" that isn't one
The idea usually goes like this: the new physician starts seeing patients, and the claims go out under a credentialed colleague's NPI until the paperwork clears. It is not a workaround. A claim has to name the clinician who actually provided the service.
Medicare does allow substitute billing, in two forms. Under a reciprocal billing arrangement (modifier Q5) or a fee-for-time arrangement, formerly called locum tenens (modifier Q6), the regular physician bills for a substitute's services while the regular physician is unavailable. Either way, the substitute can't cover for more than 60 continuous days (Medicare Claims Processing Manual ch. 1, §30.2.10 and §30.2.11; CGS locum tenens guidance). The one exception is a physician called to active duty in the Armed Forces. A group can also use Q6 for a temporary replacement after a physician leaves, still capped at 60 days.
A new hire fits none of this. No regular physician is being covered, and the new physician isn't temporary. The American Academy of Ophthalmic Executives puts it plainly: "Newly hired physicians, when not yet credentialed, do not qualify as locum tenens" (locum tenens fact sheet). The same fact sheet says billing under a senior partner's NPI isn't appropriate either.
Incident-to billing comes up for nurse practitioners and physician assistants. Its conditions are strict: the physician must have started the course of treatment and stay actively involved, the service needs direct supervision, and only the supervising physician may bill (Medicare Benefit Policy Manual ch. 15, §60; 42 CFR 410.26). Don't use it to fill a credentialing gap without advice from healthcare counsel.
Can a new physician bill under another doctor's NPI while credentialing?
No. A claim has to identify the clinician who provided the service. Medicare's substitute billing rules (modifiers Q5 and Q6) cover a regular physician who is unavailable, for no more than 60 continuous days, and the American Academy of Ophthalmic Executives says newly hired physicians who aren't yet credentialed don't qualify. Hold the claims instead and track each one's filing deadline.
If claims have already gone out this way, talk to healthcare counsel before you do anything else.
Holding claims: the clock is already running
Holding claims until billing opens is the safe choice. But a held claim usually ages from the date of service, not from the day you're approved, so the filing deadline keeps getting closer while you wait.
- Medicare
- 12 months from the date of service (42 CFR 424.44). The exceptions in that rule cover things like a Medicare contractor's error or a patient's retroactive entitlement, not a late enrollment.
- Texas preferred provider plans
- 95 days from the date of service, unless the contract allows longer. Miss it and the provider forfeits the right to payment (Tex. Ins. Code §1301.102).
- Texas Medicaid
- A newly enrolled provider's claims are due within 95 days of enrollment completion and within 365 days of the date of service (TMPPM Vol. 1, §6.1.4.2). It is one of the few clocks tied to enrollment.
- Colorado Medicaid
- The backdate approval letter works as the timely filing waiver (HCPF).
- Commercial plans
- Ask each plan in writing whether its filing limit runs from the date of service or from your effective date.
To see how fast that adds up: a visit on March 3 billed to a Texas PPO has to be received by June 6, whether or not the provider is loaded in the plan's system by then.
The practical rule: log every held claim with its date of service, payer and filing limit, and submit the day billing opens. You can track each held claim's filing window with the free countdown tool. Visits from before Medicare's 30-day lookback won't be paid, so don't hold those expecting payment.
Work backward from opening day
Credentialing runs in sequence, because later steps need earlier ones. Use this order as a planning guide, not a rule: every state and payer sets its own pace.
| Step | What it is | Needs first |
|---|---|---|
| 01NPI | Apply in NPPES. It's free. | Nothing. Do it first |
| 02CAQH profile | Now the CAQH Provider Data Portal. CAQH became DataSpring, powered by CAQH, in June 2026. | NPI, license |
| 03Medicare | CMS-855I for the clinician, CMS-855B for a new group (CMS). Reassignment to the group now goes on the 855I, since CMS retired the 855R. | NPI, license |
| 04State Medicaid | Each state's own enrollment. | NPI, license |
| 05Medicaid managed care plans | Each plan's credentialing. | State Medicaid enrollment |
| 06Medicare Advantage and commercial plans | Each plan credentials separately. | CAQH profile for most plans, and Medicare enrollment where a plan's contract requires it |
How long Medicare takes depends on your Medicare Administrative Contractor, and each one publishes its own processing times. See, for example, Noridian, CGS and NGS. Check your own MAC's page rather than an industry average.
A few states set rules for commercial plans. Virginia gives carriers 60 days to decide on a complete application and, on conditions, has them pay claims from the pending period at in-network rates once you're credentialed and contracted (Va. Code §38.2-3407.10:1). Texas has plans treat a physician joining an established, contracted group as in-network for payment once the required documents are in (Tex. Ins. Code ch. 1452). New York gives HMOs 60 days to decide (N.Y. Pub. Health Law §4406-d).
What credentialing help should include
Whoever does the work, your own staff or an outside service, ask these four questions before the first application goes out. Each one has an answer you can listen for, and a vague answer to any of them usually shows up later as a delay.
Do you follow up until the effective date is loaded in the payer's claims system, or stop at "approved"?
A good answer sounds like: Until the effective date is confirmed in the payer's system, in writing.
An approval letter and a billable provider record aren't the same day. Claims sent in between can deny, and every denial uses up time against the filing limit.
Who keeps the CAQH profile current?
A good answer sounds like: A named person, with each re-attestation date on a calendar.
Make sure the reminder emails go to someone at your practice, not to a former vendor, and that each plan you're applying to is allowed to see the profile.
Do you file Medicare reassignment and group linkage?
A good answer sounds like: Yes, reassignment on the same 855I as the enrollment, and the link to the group's contract with each plan.
A provider enrolled on their own but not linked to the group can still have claims deny.
How do you price: per application, and when is it charged?
A good answer sounds like: Per application, with the count and total in writing before work starts.
Quilven's answer: per application, charged only on approval.
Rules and sources last checked: 1 Nov 2026
