A timely filing denial means the insurer rejected the claim because it was submitted after the plan’s filing deadline. When the provider filed late, that is the provider’s billing error, not yours. In most cases you should not be balance-billed for a charge the insurer denied solely because the provider missed its filing window. This letter goes to the provider’s billing office: it disputes that you owe the balance and asks the provider to either prove timely submission and appeal, or write the amount off. Check the denial date and any patient-statement deadline on the documents you received.
Before you appeal
- The EOB or denial showing the claim was denied for timely filing (often a CO-29 type code).
- Any bill or statement from the provider trying to collect the denied amount.
- Proof of your role: you provided your insurance information at the time of service.
- Any submission records the provider has (clearinghouse confirmations, claim dates) — request these from the billing office.
- Your member ID, claim number, the date(s) of service, and the date of the denial.
The letter
[Your full name]
[Your address]
[City, State ZIP]
[Phone] | [Email]
[Date]
[Provider / Hospital - Billing Department]
[Address from your statement]
Re: Disputed balance - claim denied for timely filing
Patient: [Name] Member ID: [number] Group #: [number]
Claim number: [number] Date(s) of service: [dates]
Denial date: [date] Denial reason/code: [timely filing, as stated on the EOB]
To the Billing Department:
I am writing about the balance you are seeking from me for the date(s) of
service above. According to the Explanation of Benefits, my insurer denied
this claim because it was not filed within the plan's timely-filing deadline.
I provided my insurance information at the time of service. A claim denied
solely because it was submitted after the insurer's filing deadline is a
billing matter between the provider and the insurer. I dispute that I am
responsible for this balance, and I ask that you not bill me for an amount the
insurer denied for late filing.
Please do one of the following:
1. Submit proof that the claim was filed on time and appeal the denial with
the insurer; or
2. Write off the balance as a timely-filing adjustment.
Please send me written confirmation of how this account has been resolved, and
do not send this balance to collections while it is in dispute.
Enclosed in support:
- Copy of the EOB showing the timely-filing denial
- Copy of the billing statement in question
Thank you,
[Your signature]
[Your printed name]
How to send it
Send to the provider’s billing office (the address on your statement) by certified mail with return receipt requested, and keep a dated copy of everything. If you have a patient-statement or dispute deadline on the bill, act before it. If the provider still tries to collect or reports it to a credit bureau, dispute the charge in writing and keep your records, since the denial reason supports your position.
Notes. Timely-filing deadlines are set in the provider’s contract with the insurer, not in your benefits, so a missed deadline is generally the provider’s write-off (often shown with a CO-29 adjustment code). Provider contracts and many state rules discourage balance-billing patients for claims denied solely for late filing, but specifics vary, so keep your insurance information and the EOB as proof. To understand the codes, first read your denial letter; if your own insurer denied an appeal you filed, see the internal appeal letter. This is general information, not legal, medical, or insurance advice.