The August 3rd mandate was just the first wave
August 3, 2026, drew much of the tax market's attention, but it wasn't the end of the story. As of that date, issuing NF-e, model 55, and NFC-e, model 65, with information related to IBS and CBS became mandatory for companies under the normal regime, with Technical Note 2025.002 including in the layouts the fields for tax base, rates, taxes, CST, and cClassTrib. Other documents also became mandatory on the same date: CT-e, CT-e OS, MDF-e, GTV-e, NF3e, DC-e, and NFS-e Via became mandatory on August 3rd.
What many tax teams still haven't mapped out is that Joint Act RFB/CGIBS No. 4/2026 organized the mandate into a schedule staggered by document type, rather than a single cutoff for the entire country. This means that companies with diversified operations — which issue, for example, NF-e, NFCom, and NFGas at the same time — need to track different dates for each layout.
The exception that removes some service companies from the August cutoff
One point that went unnoticed by many IT and tax teams is the exception provided for those who are not ICMS taxpayers. Taxable persons for IBS and CBS who are not ICMS taxpayers only come into effect on December 1, 2026. This removes a good portion of service companies from the August cutoff. In other words: not every company under the regular regime is subject to immediate rejection starting in August — it's necessary to check the specific classification before halting invoicing as a precaution (or worse, failing to update the system due to a mistaken belief that the deadline has already passed).
The next milestone: October 1, 2026
After August, the next point of attention on the calendar is October. October 1, 2026: mandatory NFS-e for certain services subject to ISS, the Electronic Communication Services Invoice (NFCom), the Shipment Import Declaration (DIR), and the first assessment period to be reported in the Monthly Periodic Events of the Declaration of Specific Regimes (DeRE). Telecom companies, internet providers, and those handling shipment imports need to put this date on their radar now, taking into account the homologation time with the issuing system provider.
December 2026 and January 2027: the last batches
The schedule wraps up in two additional stages. NFCom and DIR take effect in October; NFGas, NFAg, and certain electronic transportation tickets in December; and the Duimp in January 2027. For Simples Nacional and MEI, the deadline for adapting the IBS/CBS fields in electronic tax documents runs until January 4, 2027, as had already been signaled by the Federal Revenue Service.
Checklist for tax, accounting, and IT teams
Before each milestone, it's worth reviewing: what is the company's actual tax classification (normal regime, ICMS taxpayer or not, Simples Nacional); which electronic tax documents the operation actually issues, beyond the NF-e; whether the ERP and the tax issuer have already received the approved updates for each layout; and whether the team has tested the full flow in a homologation environment before switching to production, since a mass rejection can halt the day's invoicing.
Keeping this control document by document, instead of treating the reform as a single August event, is what prevents surprises in October, December, and at the turn of 2027.
This content is for informational purposes only and does not replace guidance from your accounting firm, which should assess your company's specific classification for each of these dates.
Want to understand how your ERP can keep up with this schedule without setbacks? Talk to Edoo.
After August 3rd: the IBS/CBS timeline by fiscal document type through December 2026