from Office of the City it is 23,03 per 1m2 (part of your flat) if you run business from home
In 2015 the property tax rate will amount per year:
2) from the buildings or parts:
a) residential - 0,74 zł per 1 m2 of usable space,
b) associated with running a business and residential buildings or their parts destined for a business purposes - 23,03 zł per 1 m2 of usable space
My husband and I run business from home (one room of 10m2) and we pay this fee. But you can also deduct some amount of gas fee and energy. E.g. if your flat is 100m2 and you use 10m2 for your business it would be 10%.