Opinion writer

I am not a tax attorney, but this I know: Tax returns must include not only the wages, salaries and interest you earned but all income that comes your way.

Say you have a little side job and got paid in cash, or you provided service as an independent contractor and got money for it. You must report those earnings, even if the payment is less than $600.

Underreporting taxable income is a no-no that, frankly, gets the Internal Revenue Service all bent out of shape.

I offer this brief reminder on taxable income because a lot of political campaign dough has been sloshing around the District in recent years.

Some of it may have ended up in the pockets of operatives in the “shadow campaign” on behalf of Vincent Gray’s 2010 mayoral race — an off-the-books operation that some suspect was financed by businessman Jeffrey Thompson.

Now hear this: “Cash and go” may work at the check-cashing store. But the IRS doesn’t roll that way. The government wants its cut.

And where money is involved, the government is unrelenting.

Case in point: this week’s guilty plea to a criminal tax charge by an aide to former D.C. Council member — now convicted felon — Harry Thomas Jr.

Ayawna Webster helped channel $110,000 in youth grant funds to pay for an inaugural ball. The U.S. attorney’s office noted Friday that “for the fiscal year ending Sept. 30, 2009, Webster never filed federal or District of Columbia tax returns on behalf of the organization.”

See what I mean?

Or ask former D.C. Council chairman Kwame Brown, a convicted felon who has been released from home detention.

His travails aren’t over. Can’t say he wasn’t warned.

Brown pleaded guilty to bank fraud and campaign finance violations in June 2012. U.S. Attorney Ronald C. Machen Jr. closed the criminal case against him in December, making it clear that it “should not be interpreted as a clean bill of health for the 2008 Kwame Brown campaign.” Machen suggested that city campaign officials still had work to do.

Questions about money in Brown’s campaigns — where it came from, where it went and why — still loom large.

Taking up where Machen left off, the D.C. Office of Campaign Finance (OCF) this week released its final audit of Brown’s 2010 campaign, in which Brown defeated Vincent Orange in the race for council chairman.

A key finding: Brown’s campaign committee spent more than $215,000 on “consulting services” to two companies, but it couldn’t produce copies of the contracts describing the services rendered, the length of the contracts or payment agreements between the campaign and the contractors.

The money went somewhere and for something, but where and for what? The OCF wants to know who got it. The IRS may also wish to learn whether the recipients reported the payments.

The audit is in the hands of the OCF’s general counsel, said Wesley Williams, the agency’s public affairs manager. Williams advised by e-mail that the general counsel “may recommend to the Director a dismissal of the matter if there is insufficient evidence to support a violation, to the imposition of civil penalties if it is determined that a violation of the Campaign Finance Act has occurred.”

I’m betting that Brown’s campaign committee thought it had a zero cash balance according to the final audit — but now it faces a future filled with OCF-imposed civil penalties. Can the IRS be far behind?

Ironically, Brown’s trouble with the OCF was instigated by Orange (D), an at-large council member and political opponent who filed a complaint in 2010 against Brown’s campaign finance practices in 2004 and 2008 elections.

Now the feds are calling upon Orange to explain himself.

Again, the issue is money.

Last month, WUSA-TV reporter Bruce Johnson tweeted that Machen’s prosecutors were investigating a $60,000 consultant payment to Orange from a Northeast business. WUSA (Channel 9) also reported that subpoenas had been sent to Orange and business owners in Ward 5 and that prosecutors were looking into Orange’s campaign contributions beginning in 2006.

Turns out, the business is owned by Sang Oh Choi, who, with family members, has donated more than $18,000 to Orange campaigns since 2002, according to The Post’s Mike DeBonis.

Choi’s attorney, A. Scott Bolden, confirmed to me that Choi has been issued a subpoena seeking campaign finance records as well as information about consultant payments to Orange. Bolden maintains that the consultant relationship between Orange and Choi is well documented.

I’m told by someone familiar with the investigation, however, that the feds want to know what services were rendered by Orange and that they want evidence of those services. Claims of oral reports don’t seem to be cutting it with prosecutors.

I posed questions to Orange, through his office, about the subpoena and the consultant contract. After speaking with Orange, his chief of staff, James D. Brown Jr., responded by e-mail: “Please refer any questions on this subject matter to the United States Attorney’s Office.”

It’s all about the money.

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