Trump's claim that Japan provided a $550 billion 'signing bonus' as part of the trade deal is largely accurate in the sense that the agreement includes a massive Japanese investment fund under U.S. Control, though the term 'signing bonus' is a simplification and somewhat misleading.
Trump claims that Japan gave his administration a $550 billion "signing bonus" as part of the trade deal.

Investment Fund Seals Trade Deal for Japan and Expands Trump’s Influence - The New York Times
Source: nytimes.com
Key Evidence
The New York Times reports that the U.S. Will control where Japanese money is invested and keep most profits from a $550 billion fund tied to the trade deal.
nytimes.comnytimes.comInvestment Fund Seals Trade Deal for Japan and Expands Trump’s Influence Moneycontrol highlights expert surprise at the scale and nature of this arrangement within the trade agreement.
moneycontrol.commoneycontrol.comTrump’s $550 billion Japan deal stuns trade experts: What it means for US...
What the Evidence Shows
The claim can be broken down into two main components: first, that Japan provided $550 billion as part of a trade deal with the Trump administration, and second, that this amount was characterized as a 'signing bonus. ' According to multiple credible sources, including The New York Times and Moneycontrol, the trade deal includes a large Japanese investment fund valued at approximately $550 billion, which the U.S. Administration will have significant control over, including decisions on where to invest the money and retaining 90% of the profits.nytimes.comnytimes.comInvestment Fund Seals Trade Deal for Japan and Expands Trump’s Influence
moneycontrol.commoneycontrol.comTrump’s $550 billion Japan deal stuns trade experts: What it means for US...
This arrangement is unusual and has surprised trade experts due to its scale and terms. However, describing this fund as a 'signing bonus' is an oversimplification; it is more accurately an investment fund established as part of broader trade negotiations rather than a direct cash payment or bonus. The term 'signing bonus' may mislead by implying an immediate cash transfer or gift rather than a complex financial arrangement with long-term investment implications.
Therefore, while Trump's core factual assertion about the $550 billion figure and Japan's role in the deal is supported by evidence, the framing as a 'signing bonus' lacks nuance and could be seen as misleading without additional context.