# Get your SII purchase and sales register through an API

> Read your Registro de Compras (purchase register), the invoices waiting in Pendientes and the claims on invoices you issued, one API call each. A workflow can check Pendientes each weekday within the 8-day window and send last month's register to accounting.

Page: https://fous.com/automate/sii-mi-sii
Updated: 2026-11-12

Works with your own SII (Mi SII) account. Fous is an independent product.

## What you can build on SII

### Get the Registro de Compras for a period

Opens the Registro de Compras y Ventas, picks the company and tax period, presses Consultar and reads the Registro area of COMPRA.

- Takes: Company RUT, tax period (month and year)
- Returns: Purchase type, document type, supplier RUT, business name, folio, document date, net amount, VAT, total

### List invoices waiting in Pendientes

Reads the Pendientes area of COMPRA: received invoices still waiting for a recibo de mercaderías o servicios (receipt of goods or services).

- Takes: Company RUT, tax period
- Returns: Document type, supplier RUT, business name, folio, document date, received at SII, total

### Check claims on an invoice you issued

Looks up an issued invoice in the Registro de Aceptación o Reclamo de un DTE and reads the events the buyer registered on it.

- Takes: Document type, folio
- Returns: Folio, document type, buyer RUT, events (action, date), claimed or accepted

### Accept or claim a received invoice

In the Registro de Aceptación o Reclamo de un DTE, registers Acuse Recibo, Acepta contenido or one of the three reclamos on a received invoice.

- Takes: Supplier RUT, document type, folio, action
- Returns: Folio, supplier RUT, action registered, result message

## Automate SII with a workflow

A [workflow](/product/workflows) 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.

### New invoices in Pendientes, before the 8 days run out

Starts: Every weekday at 8:00

1. List the invoices in Pendientes for the current tax period.
2. Keep the ones that were not there on the last run.
3. Email you the list with supplier, folio, date received at SII and total.

### Claims on the invoices you issued, to your ERP

Starts: When your system calls the workflow's webhook with the invoices you issued this week

1. For each invoice, check its claims in the Registro de Aceptación o Reclamo de un DTE.
2. Keep the invoices with a reclamo, or with a change since the last run.
3. Post folio, buyer RUT, action and date to your ERP webhook.

### Last month's Registro de Compras, handed to accounting

Starts: On the 3rd of every month at 9:00

1. Get the Registro de Compras for the previous tax period.
2. Group the documents by purchase type and supplier with an AI step.
3. Post the documents and the totals to your accounting system's webhook.

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](/product/methods), it is one POST to /v1/runs from your backend, or a tool an AI agent calls over MCP. This is what “Get the Registro de Compras 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": "sii.cl/get_purchase_register",
    "input": {
      "company_rut": "76.543.210-3",
      "period": "2026-10"
    }
  }'
```

Example response:

```
{
  "status": "completed",
  "data": {
    "company_rut": "76.543.210-3",
    "period": "2026-10",
    "documents": [
      {
        "purchase_type": "Del Giro",
        "document_type": 33,
        "supplier_rut": "77.111.222-5",
        "business_name": "Northwind Ltda.",
        "folio": 18342,
        "document_date": "2026-10-06",
        "net_amount": 1250000,
        "vat": 237500,
        "total": 1487500
      }
    ],
    "count": 1
  }
}
```

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.

## SII’s own options

SII documents a web service that consults or registers the acceptance or claim of a received electronic invoice, for the issuer, the receiver or the current holder, signed in with a digital certificate. Electronic invoicers with a certificate can also send DTEs to SII. The Registro de Compras y Ventas is used on the site, where summaries and detail are downloaded.

| Option | What it covers | What it takes |
| --- | --- | --- |
| Web Service de Aceptación o Reclamo de un DTE | Consults or registers ACD, RCD, ERM, RFP and RFT on document types 33, 34 and 43. | Authentication with a digital certificate, as the legal representative or an authorized user of the issuer or receiver, or the holder. |
| Envío de DTE y libros de compras y ventas | Sending DTEs and the purchase and sales books to SII from an electronic invoicing system. | Being an authorized electronic invoicer with a digital certificate. |
| API RPETC | SII publishes Swagger documentation for an API of the Registro Público Electrónico de Transferencia de Créditos. | Swagger documentation at api.sii.cl, linked from SII's market invoicing page. |
| The Registro de Compras y Ventas by hand | Registro, Pendientes, No incluir and Reclamados, one company and period at a time; Descargar Resúmenes and Descargar Detalles. | RUT and Clave Tributaria, Clave Única or a digital certificate. |

Read on November 12, 2026: [Web Service de Consulta y Registro de Aceptación/Reclamo a DTE](https://www.sii.cl/factura_electronica/Webservice_Registro_Reclamo_DTE_V1.2.pdf), [Sistema de facturación de mercado](https://www.sii.cl/servicios_online/1039-1184.html), [¿Qué es el Registro de Compras (RC)?](https://www.sii.cl/preguntas_frecuentes/factura_electronica/001_003_6972.htm).

## Signing in to SII

SII signs you in to the Registro de Compras y Ventas with your RUT and Clave Tributaria, with Clave Única or with a digital certificate. A user authorized for several companies picks one company RUT for each operation. With Fous you sign in once through SII's own sign-in with your own RUT and Clave: the login is sealed with AES-256, and an expired session is signed back in.

## Worth knowing

- **8 days to accept or claim**: A buyer can act on an electronic invoice for 8 days from its receipt at SII. After 8 calendar days with no action, the invoice is presumed accepted irrevocably.
- **Acuse de recibo and reclamo exclude each other**: Once you give Acuse Recibo on an invoice you cannot claim it afterwards, and once you claim it you cannot give Acuse Recibo. A write method should run only on invoices someone has checked.
- **Large downloads arrive later**: Descargar Resúmenes and Descargar Detalles are not always immediate. The file is then kept in Descargas Diferidas, to download when it is ready.
- **The F29 proposal updates the next day**: Non-electronic documents loaded into the Registro de Compras show at once, but reach the F29 proposal the next day. A new CSV upload replaces all non-electronic documents loaded before.

## More in Government: Latin America

- [Mis Comprobantes](https://fous.com/automate/mis-comprobantes.md)
- [Facturación Electrónica DIAN](https://fous.com/automate/facturacion-electronica-dian.md)
- [Simplificación Registral](https://fous.com/automate/simplificacion-registral.md)
- [ARCA - servicios con Clave Fiscal](https://fous.com/automate/arca-servicios-con-clave-fiscal.md)
- [Portal Empresarial INFONAVIT](https://fous.com/automate/portal-empresarial-infonavit.md)
- [SIFERE Web](https://fous.com/automate/sifere-web.md)
- [Declaración en Línea (F.931)](https://fous.com/automate/declaracion-en-linea-f-931.md)
- [AFPnet](https://fous.com/automate/afpnet.md)
- [ARBA](https://fous.com/automate/arba.md)
- [SEACE](https://fous.com/automate/seace.md)
- [SECOP II](https://fous.com/automate/secop-ii.md)
- [BPS Servicios en Línea](https://fous.com/automate/bps-servicios-en-linea.md)
- [IESS - Portal de Empleadores](https://fous.com/automate/iess-portal-de-empleadores.md)
- [Oficina Virtual CCSS (SICERE)](https://fous.com/automate/oficina-virtual-ccss-sicere.md)
- [SUIR](https://fous.com/automate/suir.md)
- [Previred](https://fous.com/automate/previred.md)
- [Aportes en Línea](https://fous.com/automate/aportes-en-linea.md)
- [SOI](https://fous.com/automate/soi.md)
- [SIPARE](https://fous.com/automate/sipare.md)
- [DGI Servicios en Línea](https://fous.com/automate/dgi-servicios-en-linea.md)
- [e-Tax 2.0](https://fous.com/automate/e-tax-2-0.md)
- [Agencia Virtual SAT](https://fous.com/automate/agencia-virtual-sat.md)
- [Oficina Virtual DGII](https://fous.com/automate/oficina-virtual-dgii.md)
- [Portal del SAT (Factura Electrónica)](https://fous.com/automate/portal-del-sat-factura-electronica.md)
- [SRI en Línea](https://fous.com/automate/sri-en-linea.md)
- [SUNAT Operaciones en Línea (SOL)](https://fous.com/automate/sunat-operaciones-en-linea-sol.md)
- [TRIBU-CR](https://fous.com/automate/tribu-cr.md)
- [Declaraciones y Pagos (SAT)](https://fous.com/automate/declaraciones-y-pagos-sat.md)
- [DIAN MUISCA](https://fous.com/automate/dian-muisca.md)

Other industries: [SIMPL](/automate/simpl), [Road Transport Posting Declaration Portal](/automate/road-transport-posting-declaration-portal), [Planning Portal](/automate/planning-portal), [Odyssey File & Serve](/automate/odyssey-file-and-serve), [UWM EASE](/automate/uwm-ease), [EIV](/automate/eiv).

## Frequently asked questions

### Does SII have an API?

For electronic invoices, yes. SII documents a web service to consult or register the acceptance or claim of a received DTE, used with a digital certificate, and invoicers with a certificate send DTEs to SII. The Registro de Compras y Ventas itself is used on the site, with summary and detail downloads.

### What is the difference between Registro, Pendientes, Reclamados and No incluir?

Registro holds your purchases, classed Del Giro by default. Pendientes holds invoices still waiting for a recibo de mercaderías o servicios, Reclamados those you claimed within 8 days, and No incluir those you chose to leave out, which give no VAT credit.

### Can I give acuse de recibo on an invoice in the previous month?

Yes, when the invoice bills guías de despacho from the previous month. It must be generated in the first 10 days of the month with an issue date in the previous month, refer to a guía de despacho from that month and be payable on credit.

### Can I complement the RCV on the day I file my F29?

Yes. SII says you can complement the Registro de Compras y Ventas on the same day you file and pay Formulario 29.

### Is Fous affiliated with Servicio de Impuestos Internos?

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

Fous is an independent product: it is not affiliated with, endorsed by or sponsored by the operator of SII (Mi SII) (Servicio de Impuestos Internos). 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.