IBS/CBS Reference Rate Estimated at 27.91%: What Changes (and What Doesn't) in the Tax Reform Timeline

CGIBS projects combined rate of 27.91% for IBS and CBS

The IBS Steering Committee (CGIBS) released a new estimate for the so-called reference rate of IBS and CBS — the percentage that, starting in 2027, tends to become the standard for charging the new consumption taxes. The figure presented is 27.91%, combining the state/municipal (IBS) and federal (CBS) shares.

The figure draws attention because the estimate presented by the Steering Committee is higher than the 26.5% limit established by Complementary Law No. 214/2025 for the sum of the IBS and CBS reference rates. Until now, the market had been working with projections around 26.5% (8.8% for CBS and about 17.7% for IBS), so the new number represents a significant increase over the legal cap.

Understand the process: where this number comes from and who actually decides

It's important to separate what is already fact from what is still projection. The reference rate is not set by CGIBS: the definition of the final reference rate will continue to follow the process set forth in Complementary Law No. 214/2025, with the participation of the Federal Revenue Service, the Federal Court of Accounts (TCU), and the Federal Senate. In practice, the flow works as follows:

• The Federal Revenue Service and CGIBS calculate and approve the technical estimate;
• Next, after conducting the analysis and approval of the calculations, the TCU will forward the proposal to the Federal Senate, the body responsible for defining the reference rate;
• The Senate then sets the rate through its own resolution, as provided for in Article 349 of Complementary Law 214/2025.

One calendar point deserves the attention of those handling tax compliance: exceptionally in 2026, the deadlines for this procedure were extended by 45 days, meaning the approved proposal will be sent to the Senate by October 30. In other words, the final shape of the reference rate should only become clearer in the last quarter of the year.

What happens if the 26.5% cap is actually exceeded

Complementary Law 214/2025 does not leave this situation unaddressed. As the law itself states, should the official estimates exceed this cap, it will be up to the federal Executive Branch, after consulting CGIBS, to submit to the National Congress an adjustment proposal — which may involve revising special tax regimes, tax benefits, or other mechanisms to contain the projected tax burden. This is a political and technical process that remains open and is expected to dominate much of the legislative debate through the end of the year.

What doesn't change for those issuing tax documents in 2026

For fiscal and IT teams, this news changes nothing in the short term. 2026 remains the test year for the reform, with rates fixed by law: throughout 2026, during the testing phase, IBS is charged at 0.1% and CBS at 0.9%, with no direct or immediate relation to the 27.91% figure under discussion. Charging based on the final reference rate will only take effect starting in 2027, with the gradual introduction of IBS over the following years.

Still, there's real reason to keep a close watch: any variation in the reference rate directly affects ERPs' tax calculation engines, CST/cClassTrib tables, credit sizing, and companies' pricing planning for the full transition period, which runs through 2033. Tax teams should treat the 27.91% figure as a warning sign to review internal tax burden projections, without any need for urgent action in issuance systems — the formal decision still depends on the TCU and the Senate.

This content is for informational purposes only and does not replace guidance from your accounting or tax team, who should assess the specific impacts of the reference rate on your company's planning.

The Edoo team closely monitors every stage of IBS/CBS regulation to keep your ERP's tax modules always aligned with the official Technical Notes and schedules. Talk to Edoo and find out how to prepare your company for the decisive phase of the Tax Reform.