The Buzón Tributario (Tax Mailbox) is the official communication system between the SAT and taxpayers in Mexico. It functions as a mandatory digital channel through which the SAT sends notifications, requirements, and messages of interest, and where taxpayers can submit requests and queries. Its activation is mandatory, and failure to do so can result in significant fines.
What Is the Tax Mailbox?
The Tax Mailbox is a digital platform created by the SAT that functions as an official messaging system between the tax authority and taxpayers. It was established in the Federal Tax Code and its use is mandatory for all individuals and legal entities registered in the RFC.
Unlike conventional email, notifications received through the Tax Mailbox have legal validity and produce legal effects. This means that if the SAT sends you a requirement through this channel, it is considered legally notified even if you haven't read it.
What Is It Used For?
The Tax Mailbox has multiple functions:
Receiving official notifications: Information requirements, invitations to regularize situations, audit actions.
Receiving SAT notices: Legislative changes, administrative facilities, important deadlines.
Article 69-B notifications: If your company is presumably listed as EFOS or EDOS, the notification arrives through this channel.
Submitting requests: Applications, clarifications, and appeals before the tax authority.
Consulting fiscal information: Status of procedures, refund status, tax credits.
Receiving payment proposals: The SAT can send personalized tax regularization proposals.
How to Activate the Tax Mailbox
Requirements:
Active RFC
Valid e.firma or SAT Password
Email address and cell phone number to receive alerts
Process:
Go to sat.gob.mx
Navigate to "Buzón Tributario"
Log in with your RFC and e.firma or password
Register at least one email address and one cell phone number
Confirm the contact methods with the verification codes you'll receive
The Mailbox will be activated and you'll receive alerts when you have new messages
Mandatory Status and Penalties
Tax Mailbox activation has been mandatory since 2020. Consequences of not activating it include:
Fines of $3,850 to $11,540 MXN for not enabling the mailbox
Fines of $1,400 to $4,200 MXN for not registering or keeping contact methods updated
Service by posting: If you don't have an active mailbox, the SAT can notify you by posting (publication at their facilities), which reduces your time and defense capacity
Impact on [Tax Compliance Opinion](/blog/opinion-cumplimiento-sat): Not having an active mailbox can affect your tax compliance opinion
Deadlines for Responding to Notifications
When you receive a notification in the Tax Mailbox:
You have 3 business days to open the message from when it was sent
If you don't open it, it is considered notified on the fourth business day
Deadlines to respond or challenge begin from the notification date
It is essential to check the mailbox frequently to avoid missing legal deadlines
Security Recommendations
Check your mailbox frequently — at least once a week
Keep updated your email address and cell phone number
Don't ignore alerts you receive by email or SMS
Keep evidence of received notifications and your responses
Enable push notifications if you use the SAT Mobile app
Importance in the Business Context
The Tax Mailbox is relevant for compliance analysis because:
A company with an active mailbox demonstrates a minimum level of fiscal formality
Unattended notifications can lead to tax debts that affect the Tax Compliance Opinion
Ignored requirements can escalate to more severe audit actions
Lack of an active mailbox may indicate a company that is not current with its obligations
At CRiskCo, we verify the comprehensive compliance of evaluated companies, including indicators derived from their interaction with the SAT. Our platform automates the query of multiple fiscal sources to provide a complete risk and compliance picture.
Want to automate fiscal compliance verification for your counterparties? [Explore our compliance solutions](/solutions/compliance).