If you sign up to work for Donald Trump's presidential campaign, you should insist that you want upfront payments in cold, hard cash.

The Washington Post reports that Trump, who is notorious for stiffing people when he's displeased with their work, is disputing $767,000 in payments that are owed to Fabrizio Lee, a polling firm run by longtime GOP strategist Tony Fabrizio.

The campaign would not offer the Post any details about why it's disputing the payment, which was revealed in its latest filing with the Federal Elections Commission.

Although Trump hired Fabrizio's firm all the way back in May, it didn't receive any actual payments from the campaign until this past September, when it was paid $624,000 for services rendered. The Post's review of its latest FEC filing shows that the campaign still owes Fabrizio Lee another $55,000 that's separate from the $767,000 it's disputing.

Trump's campaign last month was sued by the father behind the "USA Freedom Kids" singing troupe after the campaign broke a pledge to set up a merchandise table for the children at rallies.