Hospital billing under SUS and private health plans: the differences

Brazil has more than 6,300 active hospitals according to the National Registry of Health Establishments (CNES/DATASUS), and more than two thirds of them serve patients through SUS (Brazil’s public health system) and private health plans at the same time. The same shift, the same physician, the same bed. But for the billing department, these are two very different processes, with documents, tables, payers and rules that do not mix.

Mastering only one of the models leaves the hospital exposed to avoidable losses. This guide explains how billing works in each system, which differences have the greatest impact on operations and the main challenges for those who need to manage both flows.

What hospital billing is and why the payment model matters

Hospital billing is the process by which a hospital records the services it has provided and charges the payer responsible for each episode of care. What defines the operational complexity of this stage is the existence of different paying sources.

Under SUS, the payer is the government. The federal government, states and municipalities transfer funds to accredited hospitals based on the services recorded and submitted to the federal system. Amounts follow a single table, set by the government, and the hospital receives what the table determines, with no room for negotiation.

Under private health plans, the payer is a private health plan operator. Each payer has its own contract with the hospital, its own reference tables and specific audit criteria. What the hospital receives depends on what was negotiated and what the payer agrees to pay.

This difference in payer has a direct impact on the entire billing chain: the documents required, the systems used, the applicable procedure and materials tables and the defense criteria in case of a denial. Hospitals that serve both models need two billing flows running in parallel.

How hospital billing works under SUS

Billing under SUS begins at the moment of care and ends with the government’s financial transfer to the hospital. Between those two moments there is a set of documents, systems and validations that must be followed. Any inconsistency along the way results in rejection or a reduction in the amount receivable.

The role of the AIH in hospital stays

The Hospital Admission Authorization (AIH) is the document that underpins all billing for a hospital stay under SUS. It must be requested before admission and, once approved, serves as the official record of care. It contains the patient’s diagnosis, the procedures performed, the materials used and the length of stay.

At the end of the stay, the AIH is sent to the Hospital Information System (SIH/SUS), where it goes through automatic validation before generating the financial transfer. Each AIH has a ceiling amount set by the SIGTAP Table. If the real cost of the stay exceeds that ceiling, the hospital absorbs the difference, which is one of the main financial challenges for hospitals that serve SUS patients.

The APAC for high-complexity outpatient procedures

For high-complexity outpatient procedures, such as chemotherapy, radiotherapy and hemodialysis, the document used is the Outpatient Procedure Authorization (APAC). The flow is similar to the AIH: the hospital records the procedure, links it to the patient’s ICD code and sends it to the Outpatient Information System (SIA/SUS) for validation and payment.

The APAC requires prior authorization from the relevant Health Department, which adds an administrative step to the process before care even takes place.

The SIGTAP Table as the price reference

Every procedure, medication and material billed under SUS has its amount set by the SUS Table of Procedures, Medications and OPM, known as SIGTAP and maintained by DATASUS. It determines how much the hospital will receive for each service provided, without exception.

The table is public, updated periodically by the Ministry of Health and available at http://sigtap.datasus.gov.br. The historical gap between SIGTAP amounts and the real cost of procedures is a recurring topic in the debate on hospital financing in Brazil.

The submission flow to DATASUS and the financial transfer

After the monthly accrual period closes, the hospital consolidates the period’s AIHs and APACs and transmits the files to DATASUS. The system processes the information, applies the validation rules and calculates the amount to be transferred. Payment follows the calendar set by the local SUS administrator, which may be the Municipal or State Health Department, depending on the management level under which the hospital is qualified.

How hospital billing works with private health plans

Billing private health plans follows a logic that differs from SUS in almost every respect: the main document changes, the reference tables are different and each payer’s rules vary according to the contract signed with the hospital. While SUS has a single set of rules for everyone, with private health plans each payer is a world of its own.

TISS forms and the mandatory electronic standard

The central billing document with private health plans is the electronic form in the TISS standard, short for Troca de Informação de Saúde Suplementar (Supplementary Health Information Exchange). The TISS standard is defined and regulated by the ANS (Brazil’s National Supplementary Health Agency) and sets the mandatory format for every exchange of information between service providers and health plans, from the authorization request to the submission of the hospital claim.

The hospital fills out the admission, fee and hospital stay summary forms in its system and transmits them electronically to the payer within the contractual deadlines. Forms outside the TISS standard or with incorrect fields are rejected before they even reach audit.

The reference tables: CBHPM, Brasíndice and SIMPRO

While SUS has a single procedure table, private healthcare operates with multiple references.

• For medical procedures, the main one is the Brazilian Hierarchical Classification of Medical Procedures (CBHPM).

• For medications, the most widely used references are Brasíndice and SIMPRO, which list the prices charged in the hospital market.

The point to watch is that each payer defines in its contract which tables it accepts and what percentage of each it pays. The same procedure can have different amounts depending on the payer, the negotiated surgical tier and the contract clauses in force. This requires the billing specialist to know not only the tables but also the contracts of each health plan the hospital serves.

Prior authorization and payer audits

Most elective procedures in private healthcare require prior authorization from the payer before they are performed. The hospital requests authorization, the payer reviews it and, if approved, issues an authorization number that must appear on the billing form. Procedures performed without valid authorization are subject to a full denial.

In addition to prior authorization, payers carry out hospital audits of claims after submission. The payer’s auditor reviews the consistency between the diagnosis, the procedures billed and the materials used. Discrepancies between what was recorded in the medical record and what was billed are the main cause of denials with private health plans.

The payment deadline and the risk of denial

Unlike SUS, where the transfer follows a calendar set by the public administrator, with private health plans the payment deadline is set by contract. The most common cycle runs 30 days from claim submission to payment, but 45- or 60-day terms are frequent, depending on the payer and the size of the hospital.

During that interval, the payer may issue partial or full denials on items in the claim. The hospital has the right to dispute them through a denial appeal, but the process requires solid clinical documentation and precise technical arguments. Denials not appealed within the contractual deadline become final and represent a direct loss of revenue.

Differences and challenges of the two models

With both models laid out, it becomes clearer why hospitals that serve SUS and private health plans need separate billing processes. The table below summarizes the main differences:

For the hospital manager, this difference in rules has a direct operational impact. A team trained only in the SUS standard tends to make mistakes on TISS forms, and vice versa. Three fronts help reduce this risk:

1. continuous training of the billing team;

2. use of systems that integrate both flows in a single platform;

3. internal audit processes that catch errors before the claim is submitted, whether to DATASUS or to the payer.

Health plan reimbursement to SUS

When a health plan member uses the public network, the payer is required to reimburse SUS for the care provided. This obligation is set out in Article 32 of Law No. 9,656/1998, which regulates private health plans in Brazil.

The ANS cross-checks the SUS care database, provided by DATASUS, against the registry of health plan members. When it identifies a member who used the public network, it issues an Identified Beneficiary Notice (ABI) to the corresponding payer. The payer can pay the amount calculated or present a defense. The amounts collected are transferred to the National Health Fund (FNS).

For the hospital, this flow is transparent: it treats the patient normally and bills SUS as it would for anyone else. The charge to the payer is made by the ANS, with no direct involvement from the provider.

The financial impact of operating in both models

Each model has its own billing rhythm, its own payment cycle and its own causes of revenue loss. Managing both at the same time multiplies the operational complexity of the finance department.

Under SUS, the main risk is the lag: the SIGTAP Table has historically paid below the real cost of many procedures. With private health plans, the risk lies in the long payment cycle and in the denials that pile up when billing has inconsistencies.

For the manager, monitoring the denial rate separately for each model is the starting point. This number reveals where the losses are, which processes need review and where the team needs training. Without this visibility, the hospital loses revenue in both flows.

How technology reduces hospital billing losses

Billing SUS and private health plans efficiently takes more than a trained team: it takes integrated processes, systems that support both flows and an audit layer that catches errors before they become denials or rejections.

That is Rivio’s work. The platform uses artificial intelligence agents to audit hospital claims, identify inconsistencies and automate submission to payers, all within the contractual rules and technical standards of each payer. As a result, the hospital reduces denials, shortens the payment cycle and recovers revenue that used to be lost to process failures. To complement the work of the technology, Rivio keeps a team of nurse auditors who monitor and validate the processes.

FAQ: frequently asked questions about billing under SUS and private health plans

What is the difference between an AIH and a TISS form?

The AIH (Hospital Admission Authorization) is the document used to record and bill hospital stays under SUS. The TISS form is the mandatory electronic document for billing private health plans. Both record care for billing purposes, but they follow different standards, systems and rules.

Can the hospital use the SIGTAP Table to bill private health plans?

SIGTAP is the SUS procedure table and applies exclusively to public billing. With private health plans, the references are different, mainly the CBHPM for medical procedures and the Brasíndice and SIMPRO tables for medications and materials. The amounts each payer accepts depend on the contract signed with the hospital.

What happens when a health plan patient is treated through SUS?

The hospital bills SUS as usual. The ANS, in turn, identifies the care by cross-checking the DATASUS database against the registry of health plan members and charges the reimbursement directly to the payer, with no involvement from the provider.

What are the main causes of denials under SUS?

Denials under SUS stem mainly from inconsistencies in filling out the AIH or APAC: a diagnosis incompatible with the procedure billed, required fields left blank or information that differs between the medical record and the billing document.

How can hospitals that serve SUS and private health plans reduce billing errors?

The answer lies in three fronts: training the team in both models, using systems that integrate both flows and running internal audits before claims are submitted. Catching errors before they reach DATASUS or the payer is always more efficient than appealing denials afterward.