Publishing Company.....= setting up and account and registration with...ASCAP, BMI or SESAC...( you can only belong to one legally)..you need to usually have some sort of retail work out for sale to do this, I,ve been in ASCAP and have owned my own publishing company for about 5 years now and have collected a check from some work that I did too...they mail checks every quarter based on how a song does, the way you can do this is the song you are getting credits for needs to be registered.....so if you have a publishing company established you enter in the length, name of the song and who wrote it or was the producers.......
now usually you as the producer owning your own publishing company will get a maximum of 50% of any royalty that would be due in any given Quarter or 3 month period that the song is selling and spinning out on the air...ie XM, Radio, TV...out in clubs..they have some wierd calculations to arrive at what they will pay you....and the singer or rapper is entitled to the other 50%........in the case where you sold it the record label is you might have signed something that overides these numbers.....they might get the publishing and only leave you with something in the contract as far as what percentage they will pay you....thats not a good situation.......
My advice is before you sell or sign anything is to understand this aspect of the business side of things or you will find yourself shorted....for any producer especially up and coming GET THE most money upfront, its much harder to collect backend money thats why you see people that know their business when dealing with an artist or label with a budget it is nothing to get 5000 to 15000 for a Good track and a lot of times though there is none or very little royalties.....the executive producer and label are going more than likely get the credit and you will be happy with the money.....LOL