Sen. Bernie Sanders (I-Vt.) has missed the deadline to file his annual financial disclosures with the Senate, a move that continues to delay a complete examination of how his 2016 presidential bid affected his personal wealth.

Sanders's Senate office missed the annual deadline to file his personal financial disclosure on Monday, instead requesting and receiving a 20-day extension. The Vermont news blog VTDigger first reported the extension.

Those documents, when filed, will shed light on Sanders's financial situation from 2016, a pivotal year in the senator's career when he ran for president and emerged as one of the top figures in progressive Democratic politics.

It's not unusual for senators to miss the deadline. Sanders's early months in the presidential campaign are covered by his 2015 financial disclosure, and a spokesman told The Hill the extension is "routine."

But the missed deadline means a further delay on a snapshot of his 2016 finances after extra time granted throughout his presidential campaign by the Federal Election Commission (FEC).

As a senator and presidential candidate, Sanders was under two separate disclosure obligations - both the Senate Ethics Committee and the FEC-required annual disclosures for active candidates.

The first deadline for presidential candidates to submit their disclosure forms was on May 15, 2016, a deadline hit by both Democratic contender Hillary Clinton and then-GOP candidate Donald Trump. Instead of filing a disclosure of his finances up until that point, Sanders requested - and received - an initial 45-day extension and then a subsequent 45-day extension that moved the deadline to mid-August.

By then, Sanders had lost the Democratic primary to Clinton. So Sanders spokesman Michael Briggs told the Center for Public Integrity that the senator was informed that he would not have to file at all because he was no longer an active presidential candidate.

Sanders's 2015 annual report, his most recent one, shows little outside income for Sanders, while his wife, Jane Sanders, owns a collection of stocks worth no more than approximately $800,000.

The couple's 2015 liabilities include credit card debt that could top out as high as $50,000, as well as two mortgages worth up to $1 million.

Those exact values cannot be determined, since the Senate disclosures allow for broad ranges.

The delays, although fairly common among lawmakers, could potentially shed light on any additional income he received as part of his newfound celebrity, such as book royalties, as well as any loans he or his wife may have taken out.

Multiple reports have also said that the FBI is looking into allegations of fraud during Jane Sanders's tenure as president of Burlington College, which could lead to legal bills.

Megan Wilson contributed to this report.