The testing phase of the tax reform in 2026 will be crucial for companies to adapt. Even without taxation, issuing invoices with IBS and CBS requires adjustments, contract revisions, and model changes.
Credits: Political Crumbs
What is the testing phase of the tax reform?
The testing phase corresponds to the period in which companies must issue tax documents highlighting the new taxes, generate data for system calibration, and prepare internal processes for the tax transition.
In practice, by 2026 companies will need to:
Issue tax documents with CBS (0.9%) and IBS (0.1%) itemized;
Adapt systems, ERPs, and tax procedures;
Generate data to support the determination of the standard tax rate starting in 2027.
Although the new taxes do not need to be collected in 2026, the data declared will play a relevant role in the implementation of the new model.
Issuing invoices with IBS and CBS
The main operational challenge during the testing phase of the tax reform will be adapting systems and processes to correctly issue invoices with the new fields and highlights.
Who needs to adapt in 2026?
In 2026, compliance is likely to be more relevant for companies that calculate taxes outside of the Simples Nacional (Brazilian simplified tax regime), such as:
Companies under the actual profit regime; Companies under the presumed profit regime.
Companies under the Simples Nacional tax regime will generally need to begin the adaptation process starting in 2027.
Technical points of attention
In addition to highlighting IBS and CBS, it is important to review registrations and parameter settings, especially:
Tax classifications and product and service master data;
Codes such as NCM, NBS, and cClasTrib;
Internal rules for calculation and validation of issued and received invoices.
Inconsistencies at this stage can compromise simulations and decisions regarding pricing, contracts, and tax regimes.
Contract review during the testing phase of tax reform.
One of the most significant impacts will be the need to revise contracts with clients and suppliers. Under the new system, IBS and CBS will be charged “separately,” meaning they will be itemized separately on the invoice.
If the contract does not clearly state whether the price includes taxes, there may be:
Economic-financial imbalance;
Discussions regarding the pass-through of tax costs;
Need to renegotiate prices and terms.
The testing phase is the right time to identify sensitive clauses and adjust contracts before 2027.
Tax credits and their impact on the supply chain.
The new model strengthens the logic of credits, since, as a rule, everything paid in IBS and CBS on the purchase of goods and services can generate credit for the buyer.
Credit conditional on payment
A critical point is that the right to the tax credit may depend on the supplier actually paying the tax, and not just on issuing the invoice. This can lead to delays in receiving the credit and impact the buyer’s cash flow.
Therefore, in addition to reviewing issued invoices, companies should also monitor received invoices and the regularity of their partners.
Strategic supplier evaluation
During 2026, companies can use the tests to:
Evaluate suppliers that do not pass on tax credits (such as some classified under the *Simples Nacional* regime);
Decide whether to renegotiate prices, replace suppliers, or revise the purchasing strategy;
Identify credit and compliance risks within the supply chain.
Change in tax regime in 2027
Companies operating under the presumed profit regime should carefully assess how the use of tax credits will be affected and the impact on the total tax burden. In some cases, there may be incentives to reassess the tax regime starting in 2027.
To support this decision, 2026 should be used for:
Run outcome simulations using IBS and CBS;
Compare tax burden scenarios by regime;
Assess the impact on prices, margins, and competitiveness.
Penalties and ancillary obligations
Although the testing phase does not foresee immediate penalties, ancillary obligations will gain relevance. When penalties begin to be applied, the fine for non-compliance can reach 1% of the transaction value, according to warnings from experts on the subject.
It is also important to keep up with the evolution of tax document rules and templates, as some sectors may depend on specific templates that are yet to be made available.
Why the testing phase is strategic for companies
Experts point to 2026 as the year of simulations, adjustments, and reorganization. Companies that leave adaptation until the last minute may face:
Loss of competitiveness starting in 2027;
Operational errors in the issuance and receipt of invoices;
Difficulty renegotiating contracts and prices in a timely manner.
The sooner a company maps out risks and opportunities, the better prepared it will be for the complete transition, which extends until 2033.
Importance of specialized accounting support
The testing phase of the tax reform is not just a system adjustment. It involves contract review, supplier evaluation, tax parameterization, and tax planning for 2027. Specialized accounting and tax monitoring helps reduce risks, organize data, and make decisions based on realistic simulations.
Conclusion
The testing phase of the tax reform is a strategic step in preparing for the new system. In 2026, companies should adapt the issuance of tax documents, review contracts, simulate impacts, and evaluate suppliers to avoid surprises when the actual collection begins in 2027.
Keila Martins de Almeida,
Financial Activity Specialist at Contabilizaibank.