President Donald Trump pledged to forego a presidential salary, but as his second payday approaches, the White House is declining to say if the president has donated any of his earnings yet.

During the campaign, Trump promised he would take "no salary" if elected — a pledge he reiterated after he won.

"I'm not going to the take the salary," he told "60 Minutes" in November.

The Constitution, however, requires that the president receive a salary, and that it not be reduced during his term. Federal law mandates the president receive a $400,000 annual salary, paid out once a month.

Trump aides have previously said Trump would donate his salary to the Treasury Department or a charity.

More from NBC News:



HHS Sec.: 'Nobody will be worse off financially' under GOP health plan

Trump voters would be hit hardest by health care replacement plan

John Kasich critiques GOP health care plan over Medicaid cuts

MSNBC requested details and documentation about any salary donations from the White House, the Treasury Department and the Office of Personnel Management, which all declined to say whether Trump has donated any of his salary to date. (OPM referred questions to the White House.)

Last month, White House spokesperson Sarah Huckabee Sanders told the website Politifact that Trump "will be giving" his salary "back to Treasury or donating." The site noted the White House "declined to answer several inquiries into whether Trump has gotten a paycheck already."

Under the law, Trump would receive his first monthly paycheck for $33,333 in February, and another $33,333 on March 20.

Salary donations are not the only area where Trump's pledges to donate revenue are lacking transparency.

During the transition, Trump also unveiled a plan to "donate all profits from foreign governments' patronage of his hotels and similar businesses" to the Treasury Department. The plan was released by Trump's private law firm, Morgan Lewis, but no system or accounting has been released for how or when such donations will be processed or disclosed.