Patreon and Mexican taxes (Patreon)

Appearantly patreon is requesting me to have a working tax number (which I don't have since I've not worked in a while) and when I tried to enter the old one I had back in the day was rejected. Now it seems like patreon is gonna whithold 20% of my earnings as 'tax reduction'. I don't know how to fix that without getting into a messy situation with Mexican tax collectors. I still need patreon to pay rent even if I've not made enough for it in a while but it helps. Now I'm gonna make 20% less than before. I don't know what to do anymore.