WASHINGTON (Reuters) -The U.S. Treasury Department on Friday will reveal the strength of President Donald Trump's tariff revenues in its June budget data, as collections from multiple waves of new import duties start to build into a substantial government revenue source.

The budget data, due at 2 p.m. EDT (1800 GMT), is expected to show that customs receipts topped $100 billion for the first nine months of the current fiscal year for the first time.

In a preview of the results, the Congressional Budget Office forecast that gross customs receipts driven by tariffs rose by $50 billion in the first eight months of the fiscal year, which runs from October 1, 2024 to September 30, 2025.

That forecast represents a nearly 90% increase from the $55.6 billion collected in the year-ago period and implies about a $20 billion increase in June customs duties, after record collections of $22.8 billion in May.

"I think we'll see something in the neighborhood of $25 billion of customs duties for June," said Marc Goldwein, senior policy director for the Committee for a Responsible Federal Budget, a Washington-based fiscal watchdog group.

The net take from tariffs would be lower because increased tariff revenues would imply lower payroll and income tax payments, he said.

Treasury Secretary Scott Bessent earlier this week suggested a steeper ramp-up in tariff collections, telling a cabinet meeting that the U.S. had taken in about $100 billion in tariff income so far this year, with that figure possibly growing to $300 billion by the end of 2025. A Treasury spokesperson said Bessent was referring to the calendar year - essentially the period since Trump returned to office - and not the fiscal year.

Reaching $100 billion in tariff revenue from January through June would imply a much bigger June tariff haul of about $37 billion, since 2025 calendar-year gross customs duties collections through June totaled $63.4 billion, according to Treasury data.

Reaching $300 billion in tariff collections by December would imply an exponential increase in collections in the coming months and steep and broad tariff increases from current levels.

Bessent added that the CBO has estimated tariff income will total about $2.8 trillion over 10 years, "which we think is probably low."

Trump has set a new August 1 deadline for higher "reciprocal" tariff rates set to kick in on nearly all U.S. trading partners, with room for negotiations with some countries in the next three weeks for deals to lower them. Those duties will bring in "the big money," Trump said. 

Since those remarks on Tuesday, the U.S. president has put his tariff assault into overdrive, announcing 50% levies on copper imports and goods from Brazil and a 35% tariff on Canadian goods, all due to start on August 1.

The Trump administration is preparing more sector-based tariffs on semiconductors and pharmaceuticals.