CBS 2027 Tax Rate: The Clock Is Ticking Until 10/30 (TCU) and 12/15 (Senate) — What This Changes for Tax Systems

The most important field on the 2027 invoice is still blank

While the calendar of technical notes, DeRE, and Simples Nacional dominates October spreadsheets, there's one number that will determine the real size of the Tax Reform's impact on companies' cash flow: the CBS reference rate for 2027. And that number, to this day, doesn't officially exist.

The legal rite: who calculates, who validates, who decides

the Constitution and Complementary Law No. 214/2025 created a technical process to define this percentage. The Federal Revenue Service prepares the calculation proposal. The TCU (Federal Court of Accounts) validates the methodology and performs the calculations. Only after that does the Senate set the rate by resolution. On September 14, 2026, the Federal Revenue Service sent the calculation proposal for the reference rate of the Contribution on Goods and Services (CBS) established by the tax reform to the Federal Court of Accounts (TCU), without presenting a numerical estimate along with the submission.

The deadlines that apply now

The original schedule called for September 15 for the TCU to send the calculations to the Senate, but the original deadline was September 15, exceptionally extended by 45 days. As a result, the TCU's deadline to send the approved proposal to the Senate is October 30, 2026. After that, the Senate has until December 15, 2026 to set the CBS reference rate that will apply starting in January 2027. It's worth remembering that the Federal Court of Accounts does not choose the CBS percentage. Its role is technical: to approve the calculation methodology and validate the proposal sent by the Federal Revenue Service. Only after this approval does the number move on to whoever has the authority to set the rate, the Federal Senate, based on TCU Resolution No. 388/2026, published on June 10, 2026, which established the Court's internal procedures for validating the methodologies and calculations of the CBS and IBS reference rates.

What if the Senate doesn't vote in time?

The law provided a safety valve to prevent CBS from starting 2027 without a defined parameter: if the Senate does not act within the deadline, the rate calculated by the TCU will apply — a mechanism that removes the risk of a regulatory vacuum, but also means that tax teams may need to operate, even if temporarily, with a number defined technically rather than politically.

The number already circulating behind the scenes

While the official rate hasn't been released, a budget estimate has gained attention: the estimated reference rate for IBS and CBS is 27.91%, made up of 18.70 percentage points of IBS and 9.21 percentage points of CBS. The number appears in CGIBS Resolution No. 14, of July 29, 2026. It's important to stress the limitation of this number: the use of the 27.91% estimate was intended to enable budget and financial calculations, without anticipating the official definition of the reference rate. In other words, it's a planning parameter from the IBS Management Committee, not the rate that will actually be charged.

Why this shows up on your invoice today

Anyone who has already checked the NF-e layout for 2027 has noticed that the field meant to carry the CBS percentage remains open: the rule for the pCBS field must be 0.9% in 2025 and 2026 (art. 346). And the note, here, is different: Reference rate to be published for years after 2026. In practice, this confirms that systems, ERPs, and invoice issuers need to treat the 2027 CBS rate as a configurable parameter, not as a fixed value hardcoded into business rules — the update, when it comes, may arrive in December, just weeks before full collection begins.

Checklist for tax and IT teams through December

• Confirm that the ERP treats the 2027 CBS rate as a parameter, not as a constant in the code or in a fixed spreadsheet;
• Track the publication of the TCU's calculation (by 10/30) and the Senate's resolution (by 12/15), which will define the number that takes effect with the full CBS collection in January 2027;
• Review pricing and margin simulations considering ranges around the reference estimate, without treating it as final;
• Map long-term contracts that provide for tax pass-through, to already plan for an adjustment clause once the official rate is released;
• Keep the tax and accounting team aligned with IT so that the percentage update, once published, can be quickly applied in staging and production environments.

This content is for informational purposes only and does not replace guidance from your company's accounting department, which should assess the specific impact on your tax regime, sector, and operations once the final reference rate is defined.

Want to keep a close eye on how these changes affect your ERP and your tax routine? Talk to Edoo.