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FousDeclaración en Línea (F.931)

Pull your F.931 nómina and filings into your own systems

Read each period's nómina (worker list), with each CUIL's Situación de revista, days worked, Sueldo and SAC, and your Declaraciones Juradas generadas (filed returns). A workflow can email you each month's altas and bajas (hires and leavers).

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Works with your own Declaración en Línea (F.931) account. Fous is an independent product.

What you can build on Declaración en línea

  • Get the nómina for a period

    Build this

    Reads the download of all workers for one generated declaration under Consultas: each CUIL's Situación de revista, days worked and pay items.

    Takes
    Period (month and year)
    Returns
    Period, original or rectificativa, CUIL, Situación de revista, days or hours worked, Sueldo, Adicionales, Horas Extras, SAC, Vacaciones, Premios

  • List the declarations you generated

    Build this

    Reads "Declaraciones Juradas generadas" under Consultas: which periods were generated, whether original or rectificativa, and which reports can be printed.

    Takes
    From period (optional)
    Returns
    Period, original or rectificativa, reports available (Formulario 931, Acuse de Recibo, VEP, Borrador de la DDJJ)

  • Start a period's declaration as a draft

    Build this

    Chooses "Ingrese... para generar una nueva Declaración Jurada", enters the period and reads the nómina the system builds, leaving the declaration as a draft.

    Takes
    Period (month and year)
    Returns
    Period, original or rectificativa, CUIL count, CUILs added or removed since the previous period, current step

  • Send a reviewed declaration

    Build this

    Opens the draft for a period, goes through Resultado del Cálculo and F931 and confirms Envío de la DDJJ, then reads the Acuse de Recibo.

    Takes
    Period (month and year)
    Returns
    Period, original or rectificativa, sent, Acuse de Recibo available

Automate Declaración en línea with a workflow

A workflow runs your methods as one process, with nobody at the screen. A schedule or a call from your own system starts it, the steps run in order, and the result arrives in your inbox or in the systems you already use.

  • Altas and bajas in the nómina, month over month

    Build this
    Starts
    Every month on day 5 at 9:00 (Buenos Aires time)
    Step 1
    List the declarations you generated and take the most recent period.
    Step 2
    Get the nómina for that period.
    Step 3
    Keep the CUILs that were not there on the last run, and the ones that are gone.
    Step 4
    Email you both lists with each CUIL's Situación de revista and Sueldo.

  • Filed periods and rectificativas, for accounting

    Build this
    Starts
    Every weekday at 8:00 (Buenos Aires time)
    Step 1
    List the declarations you generated in Declaración en línea.
    Step 2
    Keep the periods that are new or changed since the last run, such as a new rectificativa.
    Step 3
    Post the period, original or rectificativa and the reports available to your accounting system's webhook.

  • Draft declaration ready for review

    Build this
    Starts
    When your payroll system calls the workflow's webhook with the period
    Step 1
    Start the declaration for that period as a draft, without sending it.
    Step 2
    Keep the CUIL count and the CUILs added or removed since the previous period.
    Step 3
    Email you those, with original or rectificativa, so you can review the draft.

You can run a workflow by hand on every plan, Free included. Schedules and webhook triggers come with the paid plans, from $29 a month.

Once built, one call from your code

Once you have built a method, it is one POST to /v1/runs from your backend, or a tool an AI agent calls over MCP. This is what “Get the nómina for a period” would look like.

Example request
curl https://api.fous.com/v1/runs \
  -H "Authorization: Bearer $FOUS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "method": "auth.afip.gob.ar/get_nomina_for_period",
    "input": {
      "period": "2026-10"
    }
  }'
Example response
{
  "status": "completed",
  "data": {
    "period": "2026-10",
    "type": "original",
    "workers": [
      {
        "cuil": "20-00000001-2",
        "situacion_de_revista": "1 from day 1",
        "days_worked": 30,
        "sueldo": 1450000,
        "adicionales": 120000,
        "horas_extras": 86000,
        "sac": 0,
        "vacaciones": 0,
        "premios": 50000
      }
    ]
  }
}

An example with invented data, not a ready-made endpoint. The method exists in your organization once you build it, and its name, inputs and fields follow your request.

Declaración en línea’s own options

ARCA requires every private employer to prepare the Formulario 931 in Declaración en línea, signed in with Clave Fiscal. Its catalog of SOAP web services lists trabajo_f931, for F931 declarations registered in the social security system, reached with an X.509 certificate through WSAA; ARCA notes some services need special authorizations and agreements.

OptionWhat it coversWhat it takes
trabajo_f931 web serviceDeclaraciones Juradas F931 registered in the social security system, over SOAP.A free X.509 certificate from ARCA and a WSAA access ticket valid 12 hours. Some services need special authorizations from ARCA.
SICOSS aplicativoDeclarations for periods before February 2007 and rectificativas por novedad, which Declaración en línea does not make.The SICOSS program, with the declaration then presented to ARCA.
Declaración en línea by handGenerating, reviewing and sending the F.931, and Consultas with the nómina as a spreadsheet or PDF and reprints of acuses and VEPs.A Clave Fiscal with the Declaración en línea service added to it.

Read on November 12, 2026: Declaración en línea: características, Catálogo de web services de ARCA, Consultas frecuentes: Declaración en Línea.

Signing in to Declaración en línea

You sign in to ARCA with your Clave Fiscal under "Ingresar con Clave Fiscal", and the Declaración en línea service must be added to that Clave Fiscal before you can open it. With Fous you sign in once through ARCA's own sign-in with your own Clave Fiscal: the login is sealed with AES-256, code and AI agents never see it, and an expired session is signed back in.

Worth knowing

The nómina comes from Simplificación Registral
You cannot add or remove a worker in Declaración en línea. Altas and bajas are reported in Simplificación Registral first, and the next declaration picks them up.
Original or rectificativa is decided for you
When you enter a period, the system makes an original or a rectificativa depending on whether that period was already presented. Only rectificativas por nómina completa are made here; rectificativas por novedad need SICOSS.
Retenciones can only go down in a rectificativa
A rectificativa can lower or remove the retenciones already declared, never raise them. Retenciones left out of a period go in the next period's declaration.
No Situación Activo with zero Sueldo
The declaration cannot include a worker in Situación Activo with Sueldo 0,00. Such a worker goes in with code 14, Reserva de Puesto, instead.

More in Government: Latin America

Other industries: ICP Smart Services, EPREL, Urssaf compte employeur, webDEALER, Simplifile, Wide Area Workflow.

Frequently asked questions

Not for preparing the return: ARCA has every private employer make the F.931 in Declaración en línea. ARCA's web service catalog lists trabajo_f931, a SOAP service for F931 declarations registered in social security, reached with an X.509 certificate through WSAA. ARCA notes some services need special authorizations.

Yes. Under "Ingrese... para consultar... sus Declaraciones Juradas generadas" you can view or reprint the Formulario 931, the Acuse de Recibo, the VEP, the Borrador de la DDJJ, the report of all CUILs and the data for one CUIL.

Yes. Consultas downloads the data of all labour relationships as a PDF in one piece, and as a spreadsheet of all workers with their bases imponibles, aportes and contribuciones, Situación de revista, days worked, Sueldo, Adicionales, Horas Extras, SAC, Vacaciones and Premios.

Declaración en línea offers to generate a VEP (Volante Electrónico de Pago) through the Presentación de DDJJ y Pagos service. The balance is paid by electronic transfer of funds or at an authorized bank.

No. Fous is an independent product. You use it with your own Clave Fiscal, and a method reads and does only what that account can.

Put Declaración en Línea (F.931) behind an API call

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Read nextAFPnetARBASEACEICP Smart ServicesHow methods workHow workflows run

Fous is an independent product: it is not affiliated with, endorsed by or sponsored by the operator of Declaración en Línea (F.931) (Agencia de Recaudación y Control Aduanero (ARCA, ex AFIP)). The name is used only to say which system this page is about. Something here wrong or out of date? Write to legal@fous.com.