it’s not 15% of market sale, it’s 15% of base price.
So when you produce an item and you sell it : your gain is actually soldprice*(1-(broker+stationtax)/100)-pocotax*baseprice.
if we look at construction block :
BO is 10.4k
after direct sell it’s 10.3 worth.
base price for P2 is 7.2k so 15% means -1k
=> you lose 10% of your benefit from doing this.
Now if you consider that you did not make that P2 but instead sold the P1, that makes you a net gain/loss of …? per cycle
There are lots of planets where you can get the highsec export tax down to 10% with customs code expertise skill at level 5. If you’re doing PI in highsec, that skill should be a priority. By comparison, you’ll normally pay 3%-4% export tax in Nullsec for much better planets. Some alliances will have some tax free terrestrial or barren planets available for use as factory planets.
I consume the PI I make in T2 production which significantly improves my margins for a modest investment in time. In highsec PI works best as a secondary or tertiary income stream.
15% tax on a POCO is basically highway robbery.
Contact the corp that owns the POCOs and try to sort yourself a better deal. If that doesn’t work out for you, either find other planets with a less usurious tax rate or bash the POCOs and replace them with your own.