I don't really know how to answer the question. My "job" is as a music teacher - I teach private lessons on bass and guitar, and perhaps soon starting with piano as well. I also am in multiple bands that do paid gigs. The lessons are weekly, I charge $20 per half hour, but I don't have a ton of students (started recently with it), so I don't make a lot of money from it for the time being, not like someone would make from a full time job, but I make enough to give me some financial independence.
The gigs are an unpredictable source of income. Sometimes we get high paying ones, sometimes we get lower paying ones, sometimes we get higher paying ones, or just a week or two with a -lot- of gigs. Sometimes you get things like $800 and 4 hotel rooms split between the band members, or you make all together $4000 in a weekend, other times you're playing for free (like last weekend - there was a block party in the middle of an avenue downtown where I live, and we played that for free). Then sometimes there can be stretches of time with no gigs at all.
But, seeing as music is my only source of income, does it count as "working" when I'm practicing? If so then I work pretty much all day long with small breaks. There are also band practices, jam sessions, and times where I must prepare material for private lessons.
At the same time, none of it feels like work to me -at all-. So I don't know how to answer your question. I am actually a business owner though, I do have a business license. (very small business - the private lessons) One of the bands I'm in also has a business license (which also happens to be the most lucrative band).