DUIMP and Tax Reform: the new IBS/CBS rules go into production on September 27, 2026

Foreign trade officially enters the IBS/CBS timeline

After months of adjustments to NF-e, NFC-e, CT-e, and NFS-e, the Consumption Tax Reform arrives with a set date for the Portal Único Siscomex. In a statement released on Thursday, August 20, 2026, the government confirmed that the changes to the Single Import Declaration (DUIMP) required for the implementation of IBS and CBS will go live in the production environment of the Portal Único Siscomex on September 27, 2026. The information was published through Siscomex Import News No. 089/2026, signed by the General Coordination of Customs Administration (COANA).

What changes in practice

According to the official statement, among the main changes are the requirement to inform the state (UF) and municipality of the consumption operation location for each DUIMP item, the filling out of other taxes and duties owed until the release of the goods, and changes in the way the CST and cClassTrib codes are determined. This means that a single import declaration will no longer treat the operation generically and will instead require item-by-item traceability all the way to the final destination of the goods — information that is essential for calculating the IBS, which will be administered by states and municipalities.

Another relevant change is the end of manual entry for one of the most sensitive fields in the declaration: starting with the new version going live in production, importers will no longer need to fill in the cClassTrib field for declaration items, as the code will now be automatically defined by the system based on the legal grounds selected for the operation. In the first version, this code will only appear via the query API; on-screen display is expected to arrive in a later release.

Testing environment already available

For those in charge of the integration between ERP and Siscomex, the good news is that the testing period has already begun. According to technical guidance, these changes are already available in the Training/Validation environment of the Portal Único, allowing scenarios to be simulated before the switch to production. The weekly tax reform bulletin reinforces the recommendation: importing companies should take advantage of the testing period already available in the training environment of the Portal Único Siscomex to assess impacts on their ERPs, foreign trade systems, API integrations, and internal records, ensuring that the necessary information is available before going live in production.

How this change fits into the overall timeline

This DUIMP update is not an isolated event. It follows the same logic that has already applied to electronic tax documents since August 3, 2026, when filling in the IBS and CBS groups in the NF-e became mandatory for the regular regime. The difference is that, in the case of imports, the initial goal is preparatory: the IBS and CBS values related to foreign trade operations will be shown in the system, but within the reform's testing phase, without this alone implying immediate collection of these amounts at this stage.

What to do now

• Map, together with the tax and foreign trade departments, all imported items and their respective consumption destination (state and municipality), since this information becomes mandatory per DUIMP item.
• Test ERP integrations with the Portal Único Siscomex in the training environment before September 27.
• Review the legal grounds applicable to each operation, since the automatic determination of the CST and cClassTrib by the system will depend on them.
• Align with the customs broker and the accounting department on workflows that still depend on manual adjustment until the new version goes live in production.

Companies that import inputs or goods for resale should treat this deadline with the same attention given to the changes in NF-e: the volume of new ancillary obligations under the Tax Reform keeps growing month by month, and integration between management systems and official environments is what prevents penalties and rework at each transition stage.

This content is for informational purposes only and does not replace guidance from your accounting firm or customs broker regarding your company's specific case.

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