Pros
The great thing about having worked here is that they will train you from the ground up. You can come in with little to no tax experience and be fully trained in basics of taxes, so that is a big plus, as most companies don't do that anymore. Having worked at the IRS for a number of years looks amazing on your resume if you choose to go into the private sector or have your own tax firm someday. I appreciate that they value experience over unnecessary degrees. Good benefits, fair wages and PTO. There are opportunities to advance if you are open to relocation. Some chances to move into management locally, depending on where you are. Typically there is job security, other than the few extended shutdowns we've had in the last couple administrations. But those are rare. Paid holidays are great. No pressure to exceed expectations. Answer the phone, be accurate with customers and then go home and enjoy a nice work life balance. Also, telling the creepy guy who won't leave you alone at the bar that you work at the IRS is something I miss having the privilege to do. Now I have to use my personality.
Cons
It's super awkward when people ask you "where do you work?" Telling people you work at the IRS is definitely the worst way to introduce yourself at a party. The outside employment request is ultimately what had me move on. To accept any self employment, a side gig or other work, you must first have approval from IRS. This is fair for some fields, as they don't want you working at HR Block and also IRS. But I missed out on thousands of dollars in freelance work because they took so long to approve me doing things that had nothing to do with taxes. Not sure if this was in place then, but it was a nuisance. As you can imagine, most people calling the IRS are not happy. And being "the voice of the IRS" as a full time job can often lead to burnout. So most people only stay in this job 5-6 years maximum before heading on to new types of work.