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Product/Service Key and Unit of Measure Key from the SAT

What are these keys and why are they required?​

When generating a CFDI, it is mandatory to include two keys according to the SAT catalogs:

  • Product or service key: Describes the type of good or service being invoiced.
  • Unit of measure key: Specifies how the product is quantified (e.g., piece, hour, service).

Both keys must be included in each line item to meet the SAT’s tax requirements.

How it works​

You can assign these keys in two ways within the app:

1. Default keys​

  • If a payment or invoice doesn’t include specific keys, the default ones configured in the Facturapi App settings will be used.
  • You can set both the product/service key and the unit of measure key in the Billing Settings section of the app.
  • This option is useful when all your products share the same classification.

2. Product-specific keys​

  • You can open each product and access the Facturapi App panel.
  • From there, assign a product/service key and a unit of measure key specific to that product.
  • If you already know the codes, you can type them in directly. Otherwise, use the integrated search tool.
  • The catalog is based on the official SAT listings and is available within the app for easy lookup.

Use cases​

  • Default keys: Ideal for businesses that sell a single type of product or service and don't need to differentiate between them for tax purposes. This simplifies setup and maintenance.
  • Product-specific keys: Recommended for businesses offering multiple types of products or services that need to assign distinct tax classifications per item, ensuring accurate CFDI generation.