And while some will have to wait for the government to reopen to be paid, others will have to wait for Congress to authorize pay for the duration of the shutdown period and still others (such as contractors) will receive no pay at all for the shutdown.

Then there's the little matter of whether all deductions can be made from a paycheck. More information about the priority of an employee's deductions can be found here, since there's a real possibility that a partial check won't cover all an employee's obligations.

The good news is that retirement takes priority—although health insurance premiums fall a bit lower down on the list, after Social Security, Medicare and federal income tax deductions.

But there's also the problem with mortgages, which can have an impact on those workers who might be counting on home equity to see them through retirement, or who are in the process of selling or buying in preparation for retirement.

According to Zillow, among the 800,000 or so workers who are currently not being paid during the shutdown (about 380,000 are furloughed and another 420,000 are working without pay), total housing obligations amount to about $249 million in monthly mortgage payments and about $189 million for rent.

Not only is that a large chunk of change, but the shutdown is having an impact on FHA and Rural Housing Service loans. Zillow says that “as many as 39,000 mortgages could have been affected by today” and notes that the FHA also won't insure reverse mortgages or home-improvement loans during the shutdown.

Fannie Mae and Freddie Mac are also affected by administrative delays, which could cause loans to be denied and stall or even upend plans on both seller and buyer sides. And if worse came to worst, some could actually suffer foreclosure.

“Like Americans in the private sector, many federal employees rely on each and every paycheck to cover critical expenses, including housing,” Zillow senior economist Aaron Terrazas says in the report.

Terrazas adds, “In many parts of the country, housing affordability is already stretched and a single missed payment can begin the long process toward foreclosure or eviction—which has long-term impacts on an individual's finances and long-term economic prospects.”

Including retirement.