This seems to me to be a rather optimistic reading Other colonies can't suck tariff and tax income, only trade power. Tariff and tax income is not "no income." And as soon as you have provnices providing some Trade Power, you can significantly buffed it with Light Ships.
I really feel that what you, Comes and grisamentum say could only be read into a statement like "not much point.. you will gain far less income." That's a lot different to "won't give income."
But I would be very glad if I were wrong
Ah I see, thanks for confirming!
So the others were right, it's less income, not none.
Can you tell us if colonies will contribute trade power at 100% before they break away?
What determines the colour of the other half of the colonial nation's flag? Religion?