I then had to go to the bank and make a transfer for the TAX and ZUS each month and I didn't have to register (NIP etc) to do this
Very interesting considering how things are done by the revenue office in this country i wonder how you can pay taxes using the PIT 53 form without being a registered resident for a long time.It is possible that you could pay your taxes like this but after some time considering how long you're going to be in this country and whether you're an EU citizen or not they will advice you to get registered. Infact by EU laws you're obliged to register yourself inorder to live and work here after your initial 90days have expired. I heard about someone who got into trouble after he had been here for over 2years without registering himself. To be on the safe side with the EU laws get yourself registered.
I reside in Poland legally with my EU passport (without any Polish registration).
Infact you're not legal you're actually violating the EU laws once you've been living here for more than 90days.