Capital One representatives did not immediately respond to a request for comment.
The suit provides a glimpse into some of the details that the congressional committees hoped to glean about Mr. Trump’s finances, as well as their strategy to blur the lines between Mr. Trump as president and as private citizen.
Among the entities that Congress members have sought documents from is Mazars USA, the president’s longtime accounting firm. On April 22, Mr. Trump filed a suit to prevent Mazars from responding to a subpoena from Representative Elijah E. Cummings of Maryland, the chairman of the House Oversight and Reform Committee.
But Deutsche Bank holds one of the biggest troves of documents.
Starting in the late 1990s, it was the only mainstream financial institution willing to consistently do business with Mr. Trump. Other Wall Street banks shunned him after a series of defaults and bankruptcies saddled them with hundreds of millions of dollars in losses.
Starting in 2011, the Trump relationship was handled by the private-banking division of Deutsche Bank, which caters to the ultrawealthy. That division dispensed more than $300 million of loans to Mr. Trump and his companies, making Deutsche Bank his largest creditor. The bank also was an important lender to Mr. Trump’s son Donald Jr. and to the family of his son-in-law, Jared Kushner.
According to the suit, officials from the president’s company, the Trump Organization, tried but failed to get information about the subpoenas from congressional officials.
They learned from Deutsche Bank that the request included financial information related to “parents, subsidiaries, affiliates, branches, divisions, partnerships, properties, groups, special purpose entities, joint ventures, predecessors, successors or any other entity in which they have or had a controlling interest,” according to the suit.
The bank had intended to begin responding on May 6, the suit says.