Simples 2027 and IBS/CBS: one choice closed on Oct 15, the other runs to Oct 30

This guide is about Brazilian tax rules. Simples Nacional is Brazil's simplified tax regime for small businesses. IBS and CBS are the two new consumption taxes of Brazil's tax reform.

This October, a company under Simples Nacional had two decisions with similar deadlines and different effects. One has already closed: the election of Simples for 2027 ended on October 15. The one still open, until October 30, is the choice of the regular regime for IBS and CBS. The official guidance sums it up this way: "although the periods are similar, they deal with different choices" (Agência Gov, September 29, 2026). This guide puts the dates in one place and shows where each choice touches the system that issues invoices and closes the month.

The two choices, with the official dates

Source: Agência Gov, September 29, 2026. A company that makes no choice stays in its previous situation. And from January 1, 2027, CBS replaces PIS and Cofins, two existing federal contributions (PGFN, Brazil's National Treasury Attorney's Office).

Where the choice touches the system

This is not tax advice. The choice belongs to the company and its accountants, and what is here is what the system has to do once it is made. The choice only works if the system that issues invoices, bills and closes the month follows the decision at the same pace. Before October 30, five things are worth checking.

1. Whoever decides and whoever configures have talked. The accountants know what was chosen; whoever looks after the ERP needs to know the same day, in writing, with the date the choice takes effect.
2. The master data is ready for the choice. Products, services and customers with the tax classification reviewed by the accountants, and not inherited from years ago. Inherited master data is where an invoice goes out wrong without anyone noticing.
3. There is a test environment. Simulate issuing with the new configuration before flipping the switch, in the tax authority's approval environment, never straight in production. One test invoice for each type of operation the company carries out.
4. The cutover date has an owner. The choice applies to 2027 and the CBS changeover is on January 1. The December closing and the first invoice of January need a person responsible, by name.
5. Going back is planned for. Cancellation opens from December 3 to 20. If the choice changes, the system changes with it, with the same care as the first time.

When this guide does not apply to you

• If your company is not under Simples Nacional, the choice of the regular IBS/CBS regime in this window is not yours. The CBS changeover in January still is.
• If invoices are issued entirely by your accountants, in a system of theirs, the system checks belong to whoever operates that system. It is worth sending them this guide.
• If you are reading after October 30, 2026, the deadlines for choosing and settling have passed. Check the cancellation window (December 3 to 20) and the updated guidance on the official channels.

Checklist

• Choice (Simples and IBS/CBS) recorded by the accountants, with a date
• Person responsible for the ERP notified in writing
• Tax master data reviewed with the accountants
• Issuing simulated in the approval environment for each type of operation
• Owner of the December closing and the first January invoice defined
• Cancellation window (December 3 to 20) noted