If error messages such as “Error al calcular. Existen movimientos inconsistentes” (Calculation error. Inconsistent movements exist) or “El SBC del trabajador no es válido” (The worker’s SBC is not valid) appear when you try to calculate employer-employee contributions in the IMSS SUA system, your contribution determination process is blocked. This is one of the most frustrating problems for payroll and accounting departments, especially at bimonthly closing time. In this guide, you will find the exact causes of the error and detailed steps to fix it, generate the correct calculation, and transmit the payment file to the IMSS without issues.

The Error

The most common error messages when attempting to calculate employer-employee contributions in SUA are:

“Error al calcular. Existen movimientos inconsistentes” (Calculation error. Inconsistent movements exist)

“No se encontraron movimientos para el período” (No movements were found for the period)

“Error: El SBC del trabajador no es válido” (Error: The worker’s SBC is not valid)

“El cálculo no puede realizarse. Verifique los datos de los trabajadores” (The calculation cannot be performed. Verify worker data)

These errors appear in the Determinación de cuotas (Contribution Determination) window of SUA (Sistema Único de Autodeterminación), specifically when:

  • You select the two-month period and year to calculate and click Calcular.
  • SUA detects inconsistencies in worker data or movements.
  • The system cannot find valid records to generate the calculation.

The error prevents generating the per-worker contribution detail and therefore blocks the generation of the SIPARE file for IMSS payment.

Root Cause

The employer-employee contribution calculation in SUA depends on all worker data, affiliation movements, and reference tables being correct and synchronized. The most frequent causes of the error are:

Invalid SBC (Salario Base de Cotización)

The SBC (Base Contribution Wage) is the most critical data point for the calculation. SUA flags an error when:

Invalid conditionDescription
SBC below minimumThe registered wage is lower than the current general minimum wage
SBC above ceilingThe wage exceeds 25 times the UMA (Unit of Measurement and Update)
SBC is zero or emptyThe worker has no wage entered
SBC with incorrect decimalsThe numeric format has more than 2 decimal places or invalid characters

Inconsistent affiliation movements

  • Duplicate registrations: A worker has two or more registration movements in the same period without an intervening termination.
  • Termination without prior registration: A termination movement exists for a worker who has no registration recorded in SUA.
  • Out-of-range dates: Movements with dates before the selected period or after the current date.
  • Overlapping periods: Salary modifications with overlapping dates that create calculation conflicts.

Corrupted database

The SUA.MDB file can become damaged due to:

  • Unexpected SUA closure (power outage, force-closing from Task Manager).
  • Running SUA from an unstable network drive.
  • Antivirus conflicts blocking write access to the file.

Outdated reference tables

If SUA does not have the current year’s contribution tables, UMA, or minimum wage values, calculations fail because the contribution formulas do not match the current parameters.

Step-by-Step Solution

Step 1: Back up the database

Before making any corrections:

  1. Close SUA completely.
  2. Navigate to the C:\CobranzaSUA\ folder.
  3. Locate the SUA.MDB file.
  4. Copy the file to a backup folder (e.g., C:\Respaldos_SUA\SUA_YYYYMMDD.MDB).
  5. Verify that the copy is the same size as the original.

Step 2: Verify the period and employer registration

  1. Open SUA and confirm that the active employer registration number (registro patronal) is correct.
  2. Go to Determinación de cuotas > Cálculo.
  3. Verify that the selected two-month period and year match the period you want to calculate.
  4. If you have multiple employer registrations, make sure you are working with the correct one from the Patrones menu.

Step 3: Review workers with invalid SBC

  1. Go to Afiliación > Consulta/Modificación de trabajadores.
  2. Review the full list of active workers.
  3. For each worker, verify that the SBC is:
    • Greater than or equal to the current minimum wage (in 2025, $278.80 MXN daily for the general zone).
    • Less than or equal to 25 times the daily UMA (in 2025, 25 × $113.14 = $2,828.50 MXN).
    • A valid numeric value without extraneous characters.
  4. Correct any out-of-range SBC values directly in the worker’s record.

Step 4: Clean up inconsistent movements

  1. Go to Afiliación > Consulta de movimientos.
  2. Filter by the problematic two-month period.
  3. Identify and correct:
    • Duplicate registrations: Delete the duplicate movement, keeping only one valid registration.
    • Terminations without registrations: Record the missing registration or delete the orphaned termination.
    • Incorrect dates: Modify dates so they fall within the correct period.
  4. Go to Afiliación > Movimientos afiliatorios to add any missing movements.

Step 5: Update reference tables

  1. Check in Utilerías > Actualización de tablas that the contribution tables correspond to the current year.
  2. If the tables are outdated, download the SUA update from the IMSS portal.
  3. Install the update and reopen SUA.

Step 6: Run the calculation again

  1. Go to Determinación de cuotas > Cálculo.
  2. Select the two-month period and year.
  3. Click Calcular.
  4. If the calculation is successful, review the per-worker contribution detail to confirm the amounts are reasonable.
  5. Generate the SIPARE file from Procesos > Generación de archivo SIPARE.

Alternative Solution

If the error persists after correcting the data, the database is likely corrupted. In that case:

Repair the database with Microsoft Access

  1. Close SUA completely.
  2. Open Microsoft Access (version 2010 or later).
  3. Open the file C:\CobranzaSUA\SUA.MDB.
  4. Go to Database Tools > Compact and Repair Database.
  5. Wait for the process to complete and close Access.
  6. Open SUA and try calculating again.

Reinstall SUA and import data

If the repair does not work:

  1. Export worker and employer data from Utilerías > Exportar datos (if SUA still allows this operation).
  2. Uninstall SUA from Control Panel > Programs and Features.
  3. Delete the C:\CobranzaSUA\ folder (except your backup).
  4. Download the latest version of SUA from the IMSS portal.
  5. Install SUA following the installation wizard.
  6. Import the exported data from Utilerías > Importar datos or re-enter the employers and workers.

Direct payment via IMSS Digital

As a last resort, you can calculate and pay contributions directly on the IMSS Digital portal:

  1. Go to www.imss.gob.mx > IMSS Digital.
  2. Log in with your e.firma or NPIE (Employer Electronic Identification Number).
  3. Select Pago de cuotas obrero-patronales (Employer-employee contribution payment).
  4. The portal calculates contributions directly from the IMSS database and generates a payment reference for bank payment.

Prevention

To avoid contribution calculation errors in future two-month periods:

  • Enter movements in real time: Record registrations, terminations, and salary modifications in SUA as they occur, not at the bimonthly closing.
  • Validate each worker’s SBC: Before running the bimonthly calculation, generate an active worker report and verify that all SBC values fall within the valid range.
  • Update SUA at the beginning of each year: Contribution tables, UMA, and minimum wage values change annually. Install updates from the IMSS portal before the first calculation of the year.
  • Back up the database weekly: Schedule automatic copies of the SUA.MDB file to maintain recent restore points.
  • Do not close SUA abruptly: Always use the Exit option from the menu. Force-closing can corrupt the SUA.MDB file.
  • Compare against the IMSS assessment: After each calculation, validate the amounts against the assessment published by the IMSS. Differences indicate errors in the source data.

Other SUA errors that often occur alongside contribution calculation problems:

ProblemPossible causeQuick fix
SUA won’t open or shows component errorMissing threed32.ocx library or other OCXRegister the component with regsvr32 or reinstall SUA
Cannot generate SIPARE fileNo affiliation movements exist for the periodEnter missing movements or use the no-movements payment option
Amount differs from IMSS assessmentOutdated UMA or contribution tablesUpdate SUA tables from the IMSS portal
Error importing IDSE fileIncompatible format or expired certificateVerify file format and digital certificate validity
SUA freezes during calculationDatabase too large or damagedCompact SUA.MDB with Access or reinstall SUA

Summary

  • Errors when calculating employer-employee contributions in SUA are caused by invalid SBC values, inconsistent movements, corrupted database, or outdated reference tables.
  • Before any correction, back up the SUA.MDB file.
  • Review and correct each worker’s SBC so it falls between the minimum wage and 25 times the UMA.
  • Clean up duplicate, orphaned, or incorrectly dated movements in the period.
  • If the error persists, repair the database with Microsoft Access or reinstall SUA.
  • As an alternative, you can calculate and pay contributions directly on IMSS Digital without using SUA.
  • To prevent the problem, enter movements in real time, update SUA annually, and back up the database regularly.