If you run a business in Philly (eg, if you run a blog from your home in Philly and make any money off it) you need to get a "business-privilege license". The license costs $50 a year or $300 for a lifetime license.
So if you receive less than $50 a year from the ads, you can claimk the license as an expense on your sched C, and use the loss to reduce your other income?