I've noticed in some markets, there's an additional tax you have to pay on gross monthly income.

Some residents pay privately, others use General Assistance, and some have some state assistance.

I need money to pay off the note on the land. 

Now if you paying all cash or using a hard money loan that different.

I also use PayPal and Venmo.Some just deposit directly into my business account.I make it as easy as possible for my tenants to pay me.

The 5 percent you pay an agent to properly market a nice property will far outgain what you will lose involving someone who will come in and pretend they have the money to buy just to daisy chain it to every Facebook group in the area.

If they have been in the location for 5 years paying rent and never defaulting, then I would not require additional PG.

Actually now if someone can pay me to do it, I would do it by now LOL .... this is way more profitable than chasing CF. 

Are there additional taxes to pay? 

I offer either 10% monthly and manage everything including accepting rent and paying owners, or on call management.