Simples Nacional 2027: The September Window Decides the Opt-In Regime and IBS/CBS Collection Model

Two decisions, one single month: September 2026

The Simples Nacional calendar has changed because of the Tax Reform, and whoever handles the tax, accounting, or system parameterization of an opting company (or a candidate to join the regime in 2027) needs to act now. The traditional January option no longer exists for the next fiscal year: as of the changes brought by CGSN Resolution No. 186/2026, the request to join Simples Nacional will no longer be made in January, and companies that are not listed as opting companies as of 01/01/2027 must request the option in September 2026. The deadline is underway: the choice for Simples Nacional for the year 2027 must be made between September 1 and 30, 2026.

CGSN Resolution No. 190/2026, published in a special edition of the Official Gazette on August 10, rewrote CGSN Resolution No. 140/2018 to formally incorporate IBS and CBS into the regime, with most effects as of January 1, 2027. It is in this same regulatory text that the second point of attention for the month lies: the so-called 'hybrid Simples Nacional' option.

Two distinct options — and they must be separated in the client portfolio

It is worth reinforcing that these are two different decisions, each with its own logic: the regulation significantly changes the deadlines for expressing the options related to 2027, and two distinct options must be differentiated — the option to join Simples Nacional and the option to pay IBS and CBS under the regular regime each semester. Taxpayers who are not opting for Simples Nacional and wish to join the regime starting in January 2027 must formalize the option between September 1 and 30, 2026, effective January 1, 2027, with the possibility of cancellation until November 30, 2026.

As for those already in Simples who want to decide on IBS and CBS, they face the second choice, which is not automatic: this system is not automatic — the company opting for Simples Nacional will only be subject to the regular collection of IBS and CBS if it formalizes the corresponding option. In the hybrid model, the company remains in Simples Nacional for the other taxes, while IBS and CBS are assessed according to the rules of the regular regime, no longer being collected via the DAS and instead being assessed according to the specific rules of these taxes.

The option is binary: IBS cannot be separated from CBS

One point that often raises doubts in simulations: there is no middle ground between the two taxes. The option is binary and joint — the company that chooses the Hybrid Simples remains an opting company under Simples Nacional, but starts to assess IBS and CBS outside the DAS, under the regular regime, with debit and credit. The two taxes go together; it is not possible to take only CBS outside and leave IBS inside, or vice versa. The other taxes in the unified form remain in the DAS as usual.

The calendar becomes permanent from now on, with a window in each semester: Article 40-D of CGSN Resolution 140/2018, as amended by CGSN Resolution 190/2026, established the permanent calendar — option in September for the semester starting in January, option in March for the semester starting in July.

Deadlines, cancellation, and a possible extension

For the first half of 2027, the decision deadline is now: the option for the first half of 2027 must be made between September 1 and 30, 2026, with effects from January to June 2027, and may be canceled until November 30, 2026. Due to the publication date of the new CBS reference rate, the CGSN may postpone the final date for canceling the option. It is worth noting that the option tends to become permanent: once the option is made, the absence of renunciation in the following periods results in automatic maintenance of the regular regime.

Who is left out of the choice

Not every company in Simples takes part in this decision. Two exceptions deserve the tax team's attention: a company in Simples with revenue above the sublimit of R$ 3.6 million in the domestic market does not take part in the option — for it, IBS leaves the DAS by mandate and CBS remains inside, in accordance with Article 13-A of LC 123/2006, as worded by Article 517 of LC 214/2025, regulated by Article 9 of CGSN Resolution 190/2026. There is also a restriction related to credits: there is a significant restriction in Article 40-E — taxpayers who have received reimbursement of IBS and CBS credits in the current calendar year or the previous one are prevented from assessing IBS and CBS under the single regime. Returning to the single regime, therefore, is not automatic.

Why this matters to tax, accounting, and IT teams

The decision goes far beyond checking a box in the system. As a comment from tax compliance specialists summarizes, the decision can directly affect the use and transfer of credits, pricing, competitiveness, relationships with corporate clients, cash flow, and the effective tax cost. There is also a relevant accounting impact on revenue assessment: with Resolution No. 190, the amounts of IBS and CBS assessed and collected under the regular regime are not recorded as gross revenue for Simples Nacional purposes.

In practice, this means living with two calculation methods at the same time for those who choose the hybrid option: the amount due in the DAS continues to be calculated using the effective rate of the bracket, but with deductions for the CBS and IBS portions foreseen for that bracket — which means, in practice, living with two simultaneous calculation methods.

What to do by September 30

• Survey, client by client (or company by company, if you are the in-house team), who only needs to confirm continued participation in Simples and who needs to decide on the hybrid regime.
• Simulate the impact of IBS/CBS credits on the sales chain, especially for those selling to corporate entities under the regular regime.
• Check for outstanding tax issues with all three levels of government before submitting the option through the Simples Nacional Portal, since rejections due to debts consume part of the deadline.
• Verify whether the management system is prepared to handle two simultaneous calculation methods, in case the company chooses the hybrid option.
• Document the decision and the technical justification, considering that cancellation is only possible until November 30, 2026, and that returning to the single regime is not automatic in all cases.

This content is for informational purposes only and does not replace guidance from your accounting firm, which should assess each company's specific scenario before making any choice on the Simples Nacional Portal.

If your team needs to align its ERP with these changes in regime and assessment, talk to Edoo.