National NFS-e for Simples Nacional: CGSN postpones mandatory adoption from September to November 1, 2026 — what changes for tax, accounting, and IT

CGSN Resolution No. 191/2026 Postpones National NFS-e for Simples Nacional Until November

Those who had been preparing to migrate service invoice issuance to the National Issuer as early as September need to recalculate their timeline. On August 10, 2026, the Federal Official Gazette (Diário Oficial da União) published CGSN Resolution No. 191/2026, a short document but with direct impact on millions of service providers throughout Brazil. In practice, the rule expressly revoked CGSN Resolution No. 189 of 2026, which had set that requirement for September 1, 2026.

What changed, in detail

The original requirement had been established months earlier: the Simples Nacional Management Committee (CGSN) made the use of the National NFS-e Issuer mandatory for companies opting into Simples Nacional, effective as of September 1, 2026, under Resolution No. 189/2026, published in the DOU on April 28. With the new resolution, the deadline was extended to November 1, 2026.

This means that, until October 31, ME and EPP companies under Simples Nacional that provide services subject to ISS can continue operating through the municipal systems they already use, without risk of being blocked from issuing invoices.

Why the CGSN backed down

The official justification is operational, not legal. According to the CGSN, the extension seeks to give municipalities and taxpayers more time to complete the operational and technological adjustments needed to use the national standard. In other words, the issue was not the requirement itself, but the maturity of the integrations—on both the municipalities' side and the issuing systems' side.

What was NOT postponed

This is the point that causes the most confusion among tax and accounting teams. The resolution makes clear that the rules regarding CBS and IBS for Simples Nacional taxpayers will only take effect starting January 1, 2027. In other words, the November date deals exclusively with the switch of the issuance channel (from the municipal system to the National Issuer); filling out the new tax fields is a separate obligation, with its own timeline.

It's worth emphasizing that CGSN Resolution No. 191/2026 and Joint Act RFB/CGIBS No. 4/2026 deal with distinct obligations and should be interpreted in a complementary manner. One addresses the issuance channel; the other, the specific IBS and CBS rules applicable to taxpayers of those taxes. There is no overlap, but there is a sequence: first the channel migrates, then the tax reform fields come into play.

How issuance works under the national standard

For those who haven't yet tested the environment, it's worth remembering that NFS-e can be generated in the National Issuer through two communication methods: via the taxpayer portal (web NFS-e issuer) or through ERP software integrated with the API-type communication service with the National SEFIN. For larger portfolios, API integration tends to be the most sustainable path in the medium term, avoiding manual entry invoice by invoice.

An important reminder for clients who think this obligation is entirely new: MEI service providers have already been required to issue NFS-e under the national standard since September 1, 2023, under CGSN Resolution No. 169/2022. The national environment, therefore, has already been running in production for three years—what changes now is only the group of taxpayers required to use it.

Checklist for tax, accounting, and IT teams until November

• Confirm, client by client in your portfolio, whether the company is an ME or EPP under Simples Nacional providing services subject to ISS—this is the group affected by Resolution No. 191/2026.
• Check whether the current management or issuing system already has API integration with the National SEFIN, or whether it will depend on the manual web issuer.
• Register on the national NFS-e portal using a digital certificate or gov.br account before the last week of October.
• Issue test invoices in a staging environment to validate service codes, withholdings, and ISS rules before the transition.
• Don't confuse the channel migration (November 2026) with filling out the IBS/CBS fields, which only takes effect for Simples Nacional in January 2027—these are two separate projects with two separate deadlines.
• Keep documentation of the IBS/CBS collection option already formalized in September, since it will influence the layout that goes into production in 2027.

This content is for informational purposes only and does not replace guidance from the accounting firm responsible for the company, especially in specific cases involving classification, business activity, or municipality.

If your tax and IT team wants to arrive in November with the National NFS-e integration already validated within your ERP, talk to Edoo.