Is it mandatory to activate the Tax Mailbox?
Yes, individuals and legal entities registered in the Federal Taxpayer Registry (RFC) are required to have their Tax Mailbox activated, unless they are under an exception.
The mailbox is the communication channel between the tax authority and taxpayers in which notifications of any administrative act or resolution are carried out, which can range from promotions, requests, notices, and, where appropriate, compliance with SAT requirements.
To do this, you need to enter sat.gob.mx and click on Tax Mailbox (“B”) and access with the current Password or e-signature . Taxpayers must fill out a contact information form.
At least one email and mobile phone number are required. Subsequently, the means of contact are confirmed using a link sent by email or a code that will arrive via SMS message.
Benefits of the Tax Mailbox
Enabling and keeping the Tax Mailbox updated gives taxpayers several advantages:
-Access to a personalized portal that shows only information related to your tax regime.
-Reduction of times in procedures that were previously carried out in person.
-Legal certainty in acts, resolutions and operations issued by the SAT.
-Electronic notifications available at any time and place with an internet connection.
-Possibility of quick self-correction in case of errors or inconsistencies.
-Clear resolutions on information requirements or results of procedures.
-Facilities to receive and provide useful tax information, as well as invitations to compliance programs.
-Management of favorite content and access to sections such as “My notifications”, “My documents” and “My communications”.
In addition to complying with the law, activating it offers access to electronic notifications, reduction of in-person procedures and legal certainty in SAT resolutions, becoming a key tool to facilitate tax compliance and avoid future penalties.
How to register the Tax Mailbox?
Requirements:
RFC and password or current e-signature (legal entities only e.signature).
Valid email (up to 5).
10 digit cell phone.
Steps:
Enter sat.gob.mx and select the “Tax Mailbox” icon.
Log in with RFC and password or e.signature.
Go to “Settings” and register your emails and cell phone number.
Save the registration acknowledgment.
Confirm the media:
Email: click on the link received (72 hours).
Cellular: enter the code received via SMS in “Settings”.
By confirming both methods, your Tax Mailbox will be enabled.
How often should I update it?
Once you have the Tax Mailbox, and if the means of contact have not changed, it is not necessary to update it and it can remain that way.
It will be important to do this when the taxpayer’s email address or phone number has changed. There is no limit on the number of times to make the modification.
What is the deadline to activate the Tax Mailbox?
According to the Fiscal Miscellany 2026 published in the Official Gazette of the Federation, Mexican taxpayers have until January 1, 2027 to enable their Tax Mailbox.
Remember that the lack of authorization or the registration of incorrect means of contact may be a reason for denying specific benefits, such as the refund of balances in favor of VAT.
How much is the fine for not activating my Tax Mailbox?
Taxpayers who have not enabled the tax mailbox, or have not registered or updated their means of contact, will be subject to the penalty established in the Federal Tax Code, which ranges from 3,850 to 11,540 pesos.
