Well is not completely true, but I’m glad you ask something I like to present to the rest of the forum, so welcome to Mexican Tax Law 101.
As I suppose it’s the case in most other countries, tax legislation has many elements: one of them is the subject (that is the person who’s legally obliged to pay) and another one is the object (the act or activity which originates the obligation of the subject to pay).
So, under Mexican law, artists (the subject) must pay Income Tax only if they profit from their artistic production (the object), meaning that only when they earn money by selling their paintings to collectors, galleries and general public. So in that regard, they must determine and pay the authority every year from said earnings.
However, starting from the mid seventies according to a quick research, they can actually pay the Income Tax “in kind”, that is by donating their pictures to the state, instead of doing it with actual money, subject to some conditions.
In short, and I have some previous experience myself, Mexican Tax authority is one of the most vicious (yet rather efficient) in the World, so sadly, no matter how much paintings I produce, I’ll continue with my obligation to pay