For the first time since 2018, the federal government is heading toward a possible shutdown, leading to uncertainties and worry for its workforce. An estimated 2.1 million federal workers could see delayed paychecks, while roughly four million may not get paid at all.

There's still time to avoid any disruptions, but with a deadline of 12:01 a.m. Sunday, pessimism is growing.

There have been a number of attempts to fund the government while negotiations continue, but the latest stopgap effort failed in the House of Representatives.

"There's nothing to pay them. There is no funding. Without a spending bill, without a budget, there is no funding. If you think of it a company sense, if you don't have the money to pay your employees, you can't pay your employees," said Stephanie Rapp-Tulli, a partner and Washington, D.C.-based attorney at the law firm of Tully Rinkey.

She remembers working with clients during the last shutdown who simply didn’t know what the future held.

"People were frustrated they didn't get paid. They were on this. It wasn't their fault, and they were out for 34 days. It's really hard when you have bills and you have children, and you have to take care of that. You still have to pay for things like that," said Rapp-Tulli.

Following the 34-day shutdown five years ago, furloughed employees did not receive back pay once the government opened back up. A 2019 law would change that process.

Rapp-Tulli said anyone who doesn’t get paid during a potential shutdown should get back pay when the government opens back up.

"Most likely, everyone, let's say, goes on for period of time, similar to 2018. Hopefully not, but let's say it does. If you were furloughed, then you would likely get back pay. There's always a process after the end of a shutdown,” said Rapp-Tulli.

That’s where the legal side comes in. And it's not as simple as receiving a lump sum check when the government does open back up. It’s a process, and often a difficult one for those just simply looking to get back the payments they didn't receive.

"I really see the big impact here will be paperwork not being done correctly, or people being miscategorized. They were supposed to be on one category, they're going to be in a different, and really sorting that out, I could see there also being a delay in paying because again, like anything in the government, it takes time to go through all those steps and processes," said Rapp-Tulli.

All eyes are on Washington, D.C., with millions of workers hoping for a solution. Critical government services will continue throughout the potential shutdown, but it’s presently unclear what will be deemed essential and non-essential.