If you are new to living long-term in Antigua something "simple" like paying your basic monthly bills may seem a little confusing but it's actually not so hard. The main bills if you own a property are property taxes, water, electricity, telephone, internet, cable TV, and waste removal.
You pay your property taxes (IUSI) at the local municipality building that your property is located in. In Antigua Guatemala, it's at The City Hall building, located at the Central Park.
You pay your water bill at the local water department that your property is located in. They do not send a bill so you have to be proactive with this bill. If you are late they impose a small fine. In Antigua, it's located inside the Cesar Brañas building at the end of 5th Street West (5a Calle Poniente Final).
You can pay this bill online, or in a bank. They send a bill to your house every month.
Telephone, Internet, Cable TV
This is similar to the electricity payment. You can choose which provider you use (Claro, Tigo, etc). They all offer online and in bank payments and send you a bill monthly.