Rep. Darrell Issa — long one of the wealthiest lawmakers — is now the richest member of Congress with a reported minimum net worth of more than $355 million.

Indeed, the California Republican is worth a total that might make the Pentagon blush.

According to financial disclosure statements analyzed by CQ Roll Call, Issa’s assets increased by at least $135 million last year, and he made $59.47 million in income from those assets. That helped catapult him over last year’s richest member of Congress, Rep. Michael McCaul, R-Texas. McCaul this year boasts a minimum net worth of $114 million.

To put Issa’s $355 million net worth in perspective, the median household income in Issa’s district is $68,129, according to the 2011 American Community Survey. That means Issa is more than 5,000 times richer than his average constituent household. (He is 8,500 times richer than the median non-family income in his Southern California district, which contains many San Diego bedroom communities and a sliver of Orange County.)

Issa’s nine-figure year seems to be the result of a bull market and quirky accounting rules. The California Republican is heavily invested in high-yield bonds, and even though 2012 was a good year for such investments, it is the reporting requirement rules that make Issa’s returns seem so staggering.

Issa’s worth is speculative. The rules governing financial disclosures for members of Congress don’t really work for the super rich, given that members list assets and liabilities in ranges. For instance, if an asset such as a house were worth $920,000, the member would list it in the $500,001 to $1 million category. CQ Roll Call uses the minimum value of each item’s category to calculate lawmakers’ assets and liabilities, which means Issa could conceivably be a billionaire. For the ultra-wealthy, such as Issa, any account worth $50 million or more is counted at that $50 million threshold. Issa has seven accounts worth at least $50 million, and each one could be worth hundreds of millions of dollars.

Conversely, Issa’s net worth is clouded by two personal loans. One loan, from Union Bank, falls from $25 million to $50 million. (It is, therefore, counted as $25 million.) Another loan, from Merrill Lynch, is listed at $50 million. But because there is no range above that level, it could be considerably more, and therefore, Issa might have far greater liabilities, and far less money, than we calculate.

Last year, for example, Issa reported $175 million in debt, though that, too, is misleading because he paid off at least $75 million in debt in 2011. While lawmakers are required to report the year-end value of all assets, they must disclose liabilities that exceeded $10,000 at any point in the calendar year.

That, coupled with ranges that go from $50 million to infinity, make Issa’s finances impossible to pinpoint from disclosure forms alone.

The executive director of Citizens for Responsibility and Ethics in Washington, Melanie Sloan, told CQ Roll Call she doesn’t think the disclosure forms are “sufficient at all.”

“The greater the wealth, the less information you have about the amounts,” Sloan said. “The richer the member of Congress, the less we know about the member’s finances.”

Sloan said CREW would like to know more about Issa’s mega-loan from Merrill Lynch.

“I wonder why he would need a $50 million loan with his wealth,” she said.

But watchdogs can do little more than wonder.

There is no rule requiring Issa to disclose how much he really owes — nor how much he is really worth.

When Issa’s office was contacted for this report, it asked to see a list of CQ Roll Call’s questions for the congressman. But after reviewing the list, which ranged from questions about the usefulness of financial disclosures to Issa’s $50 million loan, the California lawmaker’s spokeswoman declined to comment.

Issa, as chairman of the House Oversight and Government Reform Committee, is a top government watchdog. He’s been a consistent critic of President Barack Obama and Attorney General Eric H. Holder Jr.

He has also made a name for himself railing against government waste. He has called federal salaries and pension plans “overly generous,” and he pushed to make federal workers pay an additional $82 billion in pension contributions over 10 years.

Issa’s “how I made my money” story is well-documented. At 17, he dropped out of high school and joined the Army. He served two years, went to college on the Army’s dime and returned to duty.

But before he went to college, Issa and his brother, William, were both charged with stealing a Maserati from a showroom. The charges were dropped.

After Issa got his degree, he went back to the Army from 1976 to 1980. He then joined the Army Reserve and used $7,000 in savings to buy a struggling electronics business. He turned the business around by making car alarms, attaching his own distinctive deep voice (“Please step away from the car”) to the company’s signature product, the Viper.

These days the Viper “protects and remote starts more vehicles than anyone else on the planet,” the company boasts. Issa made some money when he sold the company in 2000. And he has continued to make money in the stock market and with his real estate development company, Greene Properties.

In his latest disclosure, Issa reported real estate assets of at least $36 million.

An earlier version of this article misidentified Citizens for Responsibility and Ethics in Washington.