Simples Nacional companies selling to other companies (B2B) must decide between September 1 and 30, 2026: stay in the unified regime (and the B2B customer loses 28% of IBS/CBS credit) or opt into the regular IBS/CBS regime (keeping Simples for the other taxes). The decision is irreversible during 2027 — those who stay can only reassess from January 2028. Getting it wrong costs 30-50% of revenue over the year.
The single window of September 2026
Complementary Law 214/2025 and the subsequent CGSN (Simples Nacional Steering Committee) regulation set a 30-day window — between September 1 and 30, 2026 — for Simples Nacional companies to decide their 2027 IBS/CBS regime.
It is a unique decision in Brazilian tax history: no tax-regime decision has such a short window with such broad effects. Anyone who misses the deadline automatically stays in Simples — with no option to review during 2027.
Path A — Stay in Simples Nacional
It keeps the unified payment in the DAS (Simples Nacional Collection Document), with an aggregate rate ranging from 4% to 33% depending on the activity annex and revenue bracket. Operationally it stays simple — a single monthly slip, a single assessment, with no need to adapt the ERP for IBS/CBS.
The problem: the B2B customer loses the IBS/CBS credit
Under the full IBS/CBS regime, companies under Actual or Presumed Profit take a financial credit of approximately 28% on everything they buy (combined IBS+CBS rate). When they buy from a Simples supplier that stayed in the unified regime, that credit does not exist — because Simples does not break out IBS/CBS on the invoice (it pays everything via the unified DAS).
Practical result: the same good or service, bought from a Simples supplier vs a regular-regime supplier, costs the B2B customer approximately 28% more in net terms. In a business purchasing decision, that differential is decisive.
Who this path makes sense for
- Companies with an individual end customer (B2C) — an individual consumer does not take an IBS/CBS credit, so there is no competitive loss
- Retail direct to the consumer — physical stores, B2C e-commerce
- Service providers to individuals — clinics, salons, private schools for individuals
- Companies with residual B2B volume (<20% of revenue) — limited potential loss
Path B — Opt into the regular IBS/CBS regime
The company stays in Simples for the other taxes (IRPJ, CSLL, employer social security, and other federal taxes), but begins to assess IBS and CBS separately — breaking out the credit of approximately 28% on the invoice. The B2B customer takes that credit in full, preserving commercial competitiveness.
The operational costs of Path B
The company gains two new obligations:
- Monthly assessment of IBS and CBS — separate from the Simples assessment, with its own bookkeeping
- Collection via a DARF separate from the DAS — two monthly slips instead of one
In addition, there is an initial adaptation cost: the ERP must be configured to issue NF-e 5.0 with IBS/CBS fields, the tax team must be trained in the new rules, and accounting processes must be reviewed.
Who this path makes sense for
- B2B companies selling to Actual Profit — the customer is sensitive to credit; significant potential loss if you stay in Simples
- Industries with long chains — the intermediary customer needs the credit to pass it on
- Technical service providers to large companies — supplier approval may require a CNPJ under the regular regime
- Companies with a majority B2B (>60% of revenue) — the risk of customer migration is too high to stay
Decision matrix by profile
| Predominant customer profile | Typical recommendation | Reason |
|---|---|---|
| B2C (individual end consumer) | Stay in Simples | Individual customer takes no credit — no competitive loss |
| B2B Actual Profit (sells to large companies) | Opt into the regular regime | The customer loses 28% credit if you stay in Simples — high migration risk |
| B2B Presumed Profit | Case-by-case analysis | The customer is sensitive to credit only if it also migrates to the regular regime — depends on the mix |
| B2B Simples (chain between Simples) | Analysis by main customer | If the customer stays in Simples, the mutual loss nets to zero |
| Mixed B2B + B2C | Specific quantitative modeling | The decision depends on the weight and margin of each channel |
| Industry with a long chain | Opt into the regular regime | The intermediary customer loses credit → the whole chain below suffers |
Recommended quantitative modeling
Before deciding, it is advisable to model two scenarios for the next 12 months (Jan-Dec 2027):
- Stay scenario: current revenue × probability of retaining each B2B customer at a 28%-worse credit price = projected revenue
- Migrate scenario: current revenue × additional operating cost of separate IBS/CBS assessment + ERP/tax adaptation cost = projected net margin
In mid-market B2B companies with revenue above BRL 1M/month, the difference between scenarios is usually 20-40% of the annual operating margin — figures that are relevant for a strategic decision.
Risks of the wrong decision
The cost of a wrong decision in the Simples Decision 2027 is asymmetric:
- Staying wrong (should have migrated): the loss of B2B competitiveness can cost 30-50% of revenue over 2027 — customers migrate to suppliers in the regular regime
- Migrating wrong (should have stayed): adds only operating cost (separate assessment, separate collection) without necessarily affecting revenue
In industrial supply chains and in the provision of technical services to large companies, we observe a strong tendency for the buyer to require a CNPJ under the regular regime as a prerequisite for contracting from 2027. Simples companies that do not migrate may be summarily excluded from supplier-approval processes, especially in segments where the tax credit is a material part of the purchasing decision.
What NOT to do
- Do not wait until September 2026 to start the analysis — modeling takes 30-60 days if done correctly
- Do not decide with accounting alone — the decision is strategic-commercial, not just tax
- Do not copy a similar company’s decision — each customer base has a unique composition
References and official sources
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