I was reminded of this story by a question about "stolen time" that I found by accident on this community. Right now, I tried to find it again, but I failed. Anyway, my question is definitely not a duplicate, because in that case it was "stealing time" (by unit of hours), and in my case it is about "rationing time" by units of days.
I don't remember when I read it, but it was at least 30 years ago. Short fiction, but I don't remember how short. Probably not even novella length, novelette or short story.
In my story, time comes with "rationing stamps". Depending on how useful they are for society, some people have 30 days a month even in January, March, May, etc. Some have 28, some even less. Somehow, people have generally accepted this fact of life. They fall asleep some day (30th, 28th, etc.) of the month and wake up on the 1st of the next month. They know some people even live on the 31st of some months, but OK, they accept it. I am not sure I made it clear enough. During those last days of the month, in the point of view of those who "have tickets", it is not the case that those "without tickets" are seen as sleeping. They just do not exist at all. Even worse, during those days it is as if they have never existed until the beginning of the next month when suddenly it is the case that they have always existed. It is a bit hard to explain, but in the story, this is made clear.
What really becomes shocking is that there is a black-market for time where you can, not only buy a January 31st even if you don't have that "rationing stamp" but also January 32nd, 33rd, etc.
When it becomes known that some people manage to live up to 45 days a months, this becomes insufferable.
Alas, I don't remember the end....
Incidentally, if anyone can find what is the question (with answer) I found by accident, and that dealt with stealing time, I'd appreciate it, but of course this is not my question, since this would by definition be a duplicate. I think it has to do with a writer who cannot fulfil his commitments because his time is stolen from him, and therefore his days are too short...