Brazilian tax reform: evidence and workflow discipline

Brazil’s consumption tax reform has moved from debate to calendar. Constitutional Amendment No. 132 of 2023 created the new model, and Complementary Law No. 214 of 16 January 2025 (LC 214/2025) established the Tax on Goods and Services (IBS), the Contribution on Goods and Services (CBS) and the Selective Tax.

For law firms, in-house legal teams and accounting teams, the most demanding part of the law is not any single rule. It is the length of the transition.

A long transition multiplies assumptions

In broad strokes, the schedule works like this:

• 2026 is the test year, with CBS at 0.9% and IBS at 0.1%, focused on filing obligations and system adjustments.
• 2027 brings CBS fully into force and abolishes PIS and Cofins, the current federal contributions.
• From 2029 to 2032, ICMS (the state VAT) and ISS (the municipal services tax) are phased down while IBS rises in proportion.
• In 2033, IBS and CBS are fully in force, and ICMS and ISS cease to exist.

This means that for years the same company will deal with old and new taxes at once, with credit rules, tax documents and filing obligations that change from year to year. For advisers with many clients, the effect compounds: each client has its own regime, sector, special regimes and long-term contracts.

The practical consequence is that the right answer depends more and more on specific assumptions. The same question about a credit, a classification or a price pass-through can have different answers for two clients in the same sector.

Why evidence weighs more now

The new model aims for broad non-cumulativity, but taking credits and qualifying for specific regimes still depend on proper tax documentation and on the conditions set by law. Mechanisms such as collecting the tax at the point of financial settlement (often called split payment) bring the tax even closer to the document and the payment.

For advisers, that shifts the risk. The most expensive mistake is no longer not knowing the rule. It is concluding without the evidence that supports the conclusion. An opinion that affirms a right to credit without saying this depends on contracts the client has not yet sent is a fragile opinion, however well written.

Workflow discipline: four practices

Teams that handle transition periods well tend to rely less on reading speed and more on method. Four practices make the difference.

1. An assumption map for each client

Before any conclusion, record the assumptions: tax regime, sector, relevant operations, applicable special regimes and long-term contracts. Mark each one as confirmed, to verify or missing. That map is what lets you reuse analysis without repeating mistakes.

2. Evidence tied to every conclusion

Every conclusion should point to the evidence that supports it: the invoice, the contract, the clause, the statutory provision. If the evidence does not exist, the conclusion is conditional and should say so.

3. Monitoring with source and date

Regulations for the transition are still being issued. Tracking changes without recording source and date produces a pile of information nobody can cite. Good monitoring says what changed, why it matters for which clients and what to do.

4. Recorded review

Who reviewed it, what was changed and when it was approved. When the rules keep moving, the decision history protects both the client and the professional.

Where technology helps, and where it does not

Well-designed AI tools help a great deal with all four practices. They can organize the assumption map, retrieve the relevant passages from documents and legislation, prepare review material and turn open points into tasks with an owner and a deadline.

In Castilho Torres IA, that work is done by the legal-tax and fiscal-accounting assistants, together with documents and knowledge and Intelligence Reports focused on the tax reform. For tax and accounting teams, the tax and accounting solution page shows how it fits.

There is also what technology should not do. It does not replace official tax calculation and filing systems, it does not decide classifications on its own and it does not remove the need to read the statute and the regulations in force. Professional responsibility stays with the qualified professional.

What to do now

If your team has not yet organized for the transition, a realistic starting point is:

1. List the clients or business units most exposed to the change.
2. Build an assumption map with status for each one.
3. Decide who tracks regulation and how often, always recording source and date.
4. Set up a review step before any communication goes to a client.

Brazil’s tax reform will demand many answers in the coming years. The ones that hold up under challenge will be those that show clearly which assumptions and which evidence they rest on.

An informational summary of the transition schedule. Always check the statute and the regulations in force before any decision.