Timely Filing: Miss This Deadline and There Is No Getting It Back

By Brianna Hall, Director of Development, Medical Billing Center

Most billing mistakes have a path back, which is part of what makes timely filing so different from almost everything else a PT clinic deals with in the revenue cycle. A denied claim can be appealed, a rejected claim can be corrected and resubmitted, and a coding error can usually be resolved with the right documentation and a phone call to the right person at the payer. Timely filing does not work that way.

Once the deadline passes, the revenue is gone permanently, and no amount of clinical justification, appeals work, or corrected claim submissions will bring it back. This means the only real strategy with timely filing is making sure you never miss it in the first place.

What is Timely Filing

Timely filing is the deadline a payer sets for receiving your claim after the date of service.

Medicare gives providers 12 months from the date of service under federal regulation 42 CFR 424.44, which is one of the more generous windows in the industry. Most commercial payers allow somewhere between 90 and 180 days, though some contracts run as short as 60 days depending on what was negotiated. Medicaid varies by state, with some states allowing only 90 days while others extend up to a full year, and Medicare Advantage plans follow individual payer contracts rather than the Original Medicare standard, which means assuming the 12-month window applies to every Medicare patient in your schedule is a mistake that costs practices real money.

One of the most important details to understand about how this deadline works is that the clock starts on the date of service, not the date documentation was completed, not the date the billing team received the chart, and not the date the patient’s insurance information was confirmed. The moment care is delivered, the window is open and running, regardless of what else is still pending on the administrative side.

What Happens When You Miss It

When a claim is submitted after the filing deadline, the payer issues denial code CO-29, which means the time limit for filing has expired. Unlike a medical necessity denial that can be argued with clinical documentation, or an authorization denial that can sometimes be resolved through a peer-to-peer review, CO-29 has no correctable coding error underneath it. The only question the payer is reviewing is whether the claim arrived within the filing window, and if the answer is no, the decision is final with no standard appeal pathway available.

For Medicare and Medicaid patients, providers generally cannot bill the patient for a timely filing miss because late filing is treated as provider error, which means the practice absorbs the entire loss with no ability to recover it. For commercial payer patients the answer depends on the specific contract and state law, but in most cases the contract prohibits billing the patient as well, leaving the write-off as the only outcome regardless of payer type.

There are narrow documented exceptions that can occasionally allow a Medicare CO-29 to be addressed through a reopening request rather than a standard appeal, including situations such as retroactive eligibility, a Medicare Secondary Payer situation that was not identified until after the deadline, or a documented CMS administrative error. These exceptions are strictly limited, and common situations like staff turnover, high patient volume, or billing software problems do not qualify under CMS guidelines. Commercial payers rarely grant exceptions at all, which means the practical reality for most missed timely filing situations is a permanent write-off with no viable recovery path.

Why It Happens

The deadline itself is rarely the problem, which is an important distinction because it changes where a clinic needs to focus its attention. Timely filing misses are almost always the result of something that happened earlier in the workflow, and the causes tend to follow recognizable patterns across practices of every size.

A slow clinical note is one of the most consistent contributors. When documentation is not completed promptly after a visit, the chart is not ready for charge entry, and charge entry cannot happen until it is, which means every day a note sits incomplete is a day subtracted from the filing window without anyone necessarily tracking it against that deadline.

A missed insurance update creates a different version of the same problem. When a claim goes out to an incorrect payer because a coverage change was not caught during eligibility verification, it gets rejected and has to be corrected and rerouted to the right payer, and that process takes time while the original filing window continues running in the background.

Credentialing delays are a less obvious but well-documented cause that catches practices off guard more often than it should. If a rendering provider’s NPI or PTAN was not active at the time of service, the claim cannot be submitted correctly until the credentialing issue is resolved, and depending on how long that process takes, the filing window can expire before the claim is ever sent out the door.

A payer policy that nobody caught is the fourth common pattern, whether it is a shorter filing window buried in a provider contract, a claim routing requirement that was not followed correctly, or a clearinghouse issue that held claims without the billing team realizing it. Any of these can quietly create a submission backlog that pushes claims past their deadlines before the problem becomes visible.

What Actually Helps

The good news is that every one of these causes is preventable, and none of the habits that prevent them require significant resources or operational overhaul to build.

Tracking deadlines by payer rather than applying a single assumed standard across the entire schedule is the most foundational step, because without payer-specific deadline awareness there is no reliable way to know which claims are approaching a critical window until it is already too late. Verifying insurance close to the date of service rather than only at initial intake reduces the rerouting situations that eat into the filing window when coverage has changed between a patient’s first and subsequent visits. Keeping credentialing current so that a provider’s enrollment status is never the reason a claim sits unsubmitted is an operational detail that tends to be overlooked until it becomes an expensive problem. And building a documentation culture where notes are completed promptly after each visit ensures that charge entry can happen on time rather than waiting on paperwork that is days behind the appointment it reflects.

These are not extraordinary measures. They are consistent daily habits that keep timely filing from ever becoming a revenue problem in the first place, and practices that treat them as non-negotiable tend to see their CO-29 denial rate stay at or near zero over time.

MBC Keeps the Clock From Running Out

At MBC, timely filing is tracked by payer across every claim in the system, because we understand that a missed filing window is the one billing mistake with no recovery path once it has happened. We work alongside PT clinic owners to build the submission workflows and documentation habits that keep claims moving before deadlines become a concern, and we bring the payer-specific knowledge that makes it possible to manage those windows accurately across a practice’s full mix of insurance contracts.

We are led by physical therapists who understand this industry from the inside, and we are here to help you protect every dollar your clinic has already earned.