Hi everyone.  I’m a permanent resident in Catalonia,  been here for 7 years,  teaching English.  After two years doing private classes on the quiet,  this year I filed my forms to be aut?nomo because I heard through the grapevine that if you give invoices of more than 3000 euros to one company in a year,  the govt will sit up and take notice of you.
Anyway,  I started doing classes with some of the teachers at a local school and now the headmaster wants to take me on full-time to teach history.  Follow me so far?
Seems I will be doing about 30 hours a week eventually and I will be a full-time member of the staff with the same social security and tax contributions as the other teachers.
So,  my question is this…...  how do I combine this with my private classes.  I see no reason why I should stop doing private classes in the evening.  (I’m not afraid to work from 9 in the morning till 10 at night)

If all my private classes were cash I wouldn’t have a problem but I do classes with companies and issue an invoice,  sometimes for as much as 600 euros a month.   
Obviously my tax bill is determined by how much I earn,  but surely I don’t have to pay social security twice.
Any comments welcome.

Hi, I just read your message about you working in Catalonia for 7 years, etc.  I don?t know if you found the answers to your questions, there is a website that you can check: http://www.strongabogadoes.es—-if that can help you.  It?s funny because I?m trying to do what your doing.  I have been living in Seville for 5 years, I?ve got my work permit and I have been teaching private classes to all levels.  Mainly children, high school and university students.  Currently teaching at a cultural center and sometimes to companies—but prefer not to.  Anyway—I am in the process of looking for work in a school to teach children or teens, and I?m about to take a TEFL online course because in Seville most places ask for TEFL if you haven?t got a degree in English Filology.  I?d like to know if you have any advice or pointers for me?  I basically want to have a stable job teaching during the day and continue private classes in the evenings, for the reason that I want to buy a flat and I think it looks better to banks if I have a steady job to show.