When Can a Provider Start IDR After Open Negotiation Fails?

What Are the First and Last Days You Can Start IDR?

The first day is the first business day after the 30th business day of open negotiation, and the last day is the fourth business day counted from there. Under 45 CFR 149.510(b)(2), either party may start federal IDR for an item or service on which the parties have not agreed on a rate by the last day of open negotiation.

The Departments state the consequence in the preamble to the 2026 final rule. Disputes are ineligible when the parties start federal IDR after failing to complete the 30-business-day period, or after 4 business days after the end of that period.

Which Date Counts as the Day You Started?

The date of IDR initiation is the date the Secretary receives the notice of IDR initiation, not the day you prepared it. CMS's guide to the initiation web form says the same thing: the initiation date is the date the Departments receive the notice.

After you submit, the guide says the initiating party gets a confirmation email and a later email from the Federal IDR Questions mailbox confirming the initiation date. File that email with the claim. The guide also says the initiating party must give the other party a copy of the notice on the same day it submits.

File on the second or third day of the window, not the first or the last. The same guide says the web form compares the open negotiation start date you enter with the day you file, and it rejects a date fewer than 31 business days back. It also asks for an extension reason when the date is more than 34 business days back. The rule's own count and the form's check can differ by a day at the edges, so the middle of the window is safe under both.

Can You Start IDR Early, or After the Window Closes?

No to both. CMS says a dispute cannot be started until the required 30-business-day open negotiation period has ended, and it must be started within 4 business days after that period has ended, except when the Departments grant extensions.

• Early: if the other party is silent, you still wait for day 30 to pass. Silence does not shorten the period.
• Late: the dispute is ineligible.
• Extensions: CMS says a party facing extenuating circumstances can complete its extension request form and email it to the Federal IDR mailbox, and its Notices page lists any current extensions. Treat that as a rescue, not a plan.

If a deadline slipped, check the CMS notices page and email FederalIDRQuestions@cms.hhs.gov the same day rather than waiting.

What If You Settle Before the Window Opens or After You File?

A settlement before day 30 ends the matter and no IDR notice is needed. Disputing parties can also keep negotiating after IDR starts, and CMS says they can continue until the certified IDR entity decides.

If you agree on a rate after you file, the initiating party must notify the Departments within 3 business days. CMS asks for a document with the agreed total out-of-network rate, how the parties split the certified IDR entity fee if not evenly, and signatures from authorized signatories of both parties.

Filing starts the entity selection step. The steps that follow are in how to file a federal IDR dispute in the portal.

Which Claims Follow a Different Window?

Claims caught in a cooling off period follow a later window. A cooling off period follows an IDR determination and blocks the party that filed from filing again against the same other party for the same item or service.

Both the 90-calendar-day rule and the November 1, 2026 change come from CMS's timeline chart and its October 2, 2026 notice. Batching is covered in batching claims.

Did the 2026 IDR Operations Rule Change the 4-Business-Day Window?

No. The 2026 IDR operations rule changes no day count. The text in force before June 4, 2026 puts the window at 4 business days beginning on the 31st business day after the start of open negotiation, and the new text puts it at 4 business days beginning on the first business day after the last day of open negotiation. Both describe a 4-business-day window right after day 30.

What changes later is the paperwork. The new notices and the 15th-business-day payer response apply only 90 calendar days after the Departments announce the portal functionality, and offers and decisions count from final selection under the newer text. The 2026 IDR operations rule page tracks each date.

What Does the Window Look Like Around a Holiday Weekend?

A holiday weekend is where most missed windows start. This example uses made-up dates and skips Christmas Day, New Year's Day and Martin Luther King Jr. Day.

Notice that Monday, January 18 looks like a working day on many office calendars. It is a federal holiday, so the window opens a day later than a quick count suggests.

What Should Be Ready by Day 25 of Open Negotiation?

• Your final offer, and a decision on whether to hold or move it before day 30.
• The QPA, the remittance advice and the open negotiation proof, saved together.
• The claim number, service code, place of service or bill type and dates of service for every item.
• Your preferred certified IDR entity, chosen from CMS's list.
• The calendar dates for day 30 and for each day of the window, checked against federal holidays.
• A named person who files, and a backup, so a sick day does not close the window.

The same counting logic runs through the whole process, which is why we wrote how to count NSA deadlines in business days.

How We Handle the IDR Start Date

Deadline management is one part of our out-of-network reimbursement work, alongside eligibility assessment, open negotiation, dispute submissions, documentation validation and outcome tracking, under federal IDR and applicable state pathways, including Texas TDI. We track each date and keep required fees paid on time.

For ER groups, see emergency medicine billing and the out-of-network billing and IDR service. The open negotiation page covers the period before the window, and more how-tos are on the blog. To check a live claim, book a call.