If my county passes a new tax for um lets say a new jail. They staff it and build it and everything with the tax money. How come it seems the tax is there forever? Why not get rid of it when built?

Wouldn't they need to continue to collect taxes in order to fund maintenance and staff wages?

It still needs to be staffed and maintained after being built. It's not a one-time cost.

It probably didn’t pay for a jail: it paid a loan for the jail, and it will take many decades to pay off

The jail then needs staff. It needs maintenance. It needs utilities. The monetary needs just shift from construction to operation.

Taxes are unpopular necessary tools in the governmental toolbox. They are often marketed to the people as temporary necessities. And then the weeds of time grow over these intentions, people forget, and they're here to stay.

Germans still pay a sparkling wine tax. It was introduced to be able to increase military funding before WW1. They have since gone from a monarchy to a republic to a murderous dictatorship to an occupied territory to two republics side by side (at least in name, the east got rid of the tax) to a unified republic. Guess what survived for more than a century?

In addition to staffing that other people mentioned, your town isn’t paying for the jail up front. They are issue a decades-long bond and paying off construction over 30+ years.

Edit: then after the bond is paid off, they sneakily move the tax to a general fund for other services

There are three things occurring with this new facility:

1. Construction - Generally, the cost of construction is far larger than the tax for the construction project. The county may build the jail in a few years, but the taxes to pay for it usually take over a decade to pay back.

2. Operation - Once you open the facility, you have to use it. That generally requires some form of operations budget. Facilities cost money to run and intelligent governments try to plan that into building a new facility.

3. Maintenance - The building isn't going to last forever, and a lot of modern buildings need more effort to maintain them then older buildings. It is common for facilities to need significant maintenance work every 15 years. If you're going to bond to build a facility, why not include maintenance as part of the total cost of life for the facility?

Usually that kind of thing is done through a bond measure. The increased tax isn't enough to pay for a big project while it's under construction. Big projects are financed by selling bonds. Those bonds need to keep being payed back well after the project is complete.

People are giving answers to your specific hypothetical, but on a higher level, the answer is simple. The government likes having more money. Once a tax is in place, it becomes the new normal. It can be like pulling teeth to make a government roll back a tax. Groups in my local area have tried numerous times to roll back a specific tax where a government spokesperson has even said the tax is no longer fulfilling the original purpose, but removing the tax would now affect the overall budget. That has become the reason they refuse to remove it, and because neither party cares much about removing it, there's no political leverage by the voters who care about it.

Simply put because they want more money. Even though the jail is paid for at some point. They’ll just keep the tax and keep collecting and then spend it on something else.

Want to hear something that’ll really piss you off? Every year or a couple years and they’ll replace furniture and computers in city offices that don't need to be replaced. It’s totally in workable condition but they’ll spend the money anyways. Their argument is well if they don’t spend the money then they won’t get the same budget next year so they have to spend it now and yet the reality is they don’t need the equipment.

Then the city turns around, spends even more money on other crap they don’t need and then raise your taxes. Claiming They need more money.

edit: i'm getting down voted because I had a few typos that made it sound like they were spending money on things they DO need. My bad. screwed up typing is now fixed.