Donald Trump leads reporters on a tour of the Old Post Office Pavilion, soon to be a Trump International Hotel, in D.C. on March 21. (Jabin Botsford/The Washington Post)

Republican presidential candidate Donald Trump is suing the District over the tax bill for the five-star hotel he is developing at the Old Post Office Pavilion.

The suit, filed Thursday in D.C. Superior Court by attorneys for Trump, says the city is demanding an unreasonable amount for “the shell of a non-operational building undergoing a massive conversion to a hotel.”

Trump has pledged to put $200 million into the building’s renovation. Because of the significant changes inside the building, he argued, it should not be charged taxes for the past two years as a viable property. He said the renovation costs are particularly high because of his “commitment to preserve historical structures and features and the vast size of the building.”

The hotel is slated to open in September, a couple of months before the presidential election.

Typically, properties owned by the federal government are not taxed. But several years ago, the D.C. government began taxing commercial renters in federal buildings.

Republican presidential candidate Donald Trump told an audience at a rally in Portsmouth, N.H., on Feb. 4 that he wanted the hotel he is building as part of a transformation of the Old Post Office to be finished "before the big day." (Reuters)

Politico, which first reported Trump’s intention to sue, found that the District assessed the value of the Old Post Office Pavilion buildings at $98 million. Trump got that value reduced to $91 million, but efforts to get an additional reduction failed before an appeals board.

The lawsuit says that several existing luxury hotels, including the Ritz-Carlton in Georgetown, have lower tax assessments. It adds that before Trump began leasing the building, which previously held a mix of federal offices and tourist-oriented retail and restaurants, it was losing $6 million a year.

Trump attorney William Bosch called the lawsuit “a routine and customary practice that thousands of property owners in the District and many more across the country have used to ensure that their tax assessments are fairly established.”

The suit, filed by the Trump Old Post Office LLC, is not the only legal battle over the project. Trump sued celebrity chef José Andrés last year after he backed out of a restaurant project that was supposed to be part of the hotel, following Trump’s controversial comments about Mexicans at the outset of his presidential campaign.

Andrés has countersued Trump.

Jonathan O’Connell contributed to this report.