With no employer withholding on it, self-employment income is paid quarterly. Keystone Collections' dates: April 15, July 15, October 15 and January 15 (your collector's are in the rates panel). Penalty and interest are avoided by paying at least 90% of the year's tax by January 15, or four equal payments totalling 100% of last year's.
A Pennsylvania resident outside Philadelphia pays the home municipality's resident rate (municipal plus school district) on all wages and net profits, wherever the work was done. A loss from one business offsets another business's profit but never wages. The annual local return is due April 15 - even when every dollar was withheld, and even when no refund is expected.