What changes in MDF-e starting in September
Companies that issue MDF-e for road cargo transport operations on behalf of third parties have a new technical adjustment window ahead. MDF-e Technical Note 2026.001 v1.00 was published on May 29, 2026, on the SVRS portal and implements the systemic validation that will make the CIOT (Transport Operation Identification Code) mandatory in the MDF-e for all road cargo transport services provided on behalf of third parties and for compensation, under penalty of the document being rejected before it is authorized.
The legal basis already existed before the technical implementation: published in the Federal Official Gazette on April 2, 2026, SINIEF Adjustment No. 03/2026 establishes the requirement to report the CIOT in the MDF-e model 58, with legal effects starting June 1, 2026. What was missing was the systemic block in the authorizing environment — and that is exactly what NT 2026.001 brings.
Timeline: two dates to mark on the calendar
The rule follows two well-defined stages. Starting September 21, 2026, it will be available in the test environment to validate integrations and adjust internal systems, and the effective requirement in the production environment takes effect on November 23, 2026. In other words: there are only a few weeks left until testing begins and about two and a half months until the validation truly applies on SEFAZ's servers.
It's worth reinforcing that the CIOT information group (infCIOT tag) already existed structurally in the MDF-e layout; NT 2026.001 only changes its status from optional to mandatory in the defined scenarios. It's not a new field — it's a new validation block on a field that already existed.
Rejection 684: what happens if the CIOT is not filled in
Once production begins, the behavior of the authorizing environment changes in an objective way. If the MDF-e is issued without the CIOT in an operation that requires the code, the document will be rejected with error 684 — in practice, the MDF-e is not authorized, the cargo cannot leave, and the operation stops until the information is corrected and the document is properly reissued. Beyond the operational block, the company is subject to fines for failure to comply with an ancillary obligation and vehicle detention during roadside inspections.
Who needs to prepare
The requirement directly affects three profiles: carriers that hire Autonomous Cargo Transporters (TAC) or equivalent, shippers that subcontract freight, and software/ERP providers responsible for issuing the document. The rule is straightforward: the obligation always falls on whoever hires the freight — the autonomous transporter never issues the CIOT, and the responsibility falls on the contracting party, and, when there is subcontracting, it passes to the subcontractor in the relationship with whoever actually performs the transport.
It's important to remember that the CIOT requirement itself is already broader than the MDF-e validation: since May 24, 2026, with the so-called CIOT For Everyone (ANTT Resolution No. 6,078/2026), the requirement no longer applies only to hiring autonomous drivers and now covers practically all paid cargo transport operations. NT 2026.001 is the piece that connects this ANTT regulatory obligation to the SEFAZ tax environment.
Technical checklist for the coming weeks
For those handling the tax, accounting, or IT areas, the practical roadmap includes:
- Mapping which contracts and routes involve transport on behalf of third parties for compensation;
- Confirming with the team responsible for issuing MDF-e whether the system already supports filling in and linking the infCIOT group;
- Using the test environment starting September 21 to simulate real scenarios before production;
- Ensuring that the freight contracting process (where the CIOT is generated together with the Electronic Freight Payment Institution) is integrated with the tax issuance module, preventing the number from arriving after the MDF-e issuance attempt;
- Reviewing subcontracting agreements to clearly establish who is responsible for generating the CIOT at each link in the chain.
Those who treat this as an operational agenda item — not just a legal matter — will arrive in November with the process already running smoothly, without depending on last-minute fixes under the pressure of mass rejections.
This content is for informational purposes only and does not replace guidance from your accounting or legal advisory team, who should assess the specific classification of your transport operation.
If your company wants to connect freight management, tax document issuance, and accounting routines into a single environment, talk to Edoo and understand how this works in your day-to-day operations.
MDF-e: Mandatory CIOT enters homologation on 09/21 and becomes Rejection 684 at SEFAZ starting 11/23