Becoming president forced Donald Trump to resign from a slew of corporate positions, but it also appears to have netted him much more income from his Mar-a-Lago resort and from book sales.

According to a financial disclosure form released late Friday, Trump earned around $37 million this year from the Florida resort -- a seven million dollar increase from last year. 

Since coming becoming president on January 20, Trump has travelled to the Palm Beach property often and upped the membership fees substantially.

He has frequently referred to the property as the "Winter White House" and sought to promote the venue as an official presidential residence.

Trump's trips to Florida bring with them a retinue of Secret Service agents and government staff, who are reported to stay there at US taxpayers' expense.

The disclosure was made in forms released by the Office of Government Ethics. They are less detailed than full tax returns, which Trump has refused to release, breaking with decades of tradition.

The 98-page document shows that being president has also apparently increased Trump's earnings from sales of his book "The Art of the Deal" published in 1987 and that he resigned from positions in 565 companies on or around the day before becoming president.

His assets range from Pfizer stocks to a drinks company in Israel, but the disclosure also showed hundreds of millions of dollars in debt.