Even before the pandemic started, SAT required that people have an appointment to do things like register on the Tax Registry (known as the RFC) or get their digital signature (FIEL). 

Before the pandemic, appointments were available within 5 to 10 days. During the pandemic, appointments were more scarce, with new free spots opening every few weeks and no appointments available sooner than 4 weeks. 

In 2021, a twitter account (@SATsincitas) went viral, where the holder (not a government official) would post new availability of appointments which ended up making the system dysfunctional because once the twitter account would post, appointments would be depleted in minutes. 

In 2022, that twitter account was closed by Twitter and the Tax service changed the system so that when no appointments are available a “virtual line” opens. The virtual line is a form for submitting one’s email so that SAT can contact you when a new appointment is ready. 

Since January 2023, the virtual line is taking about two weeks to assign an appointment.