The US president has promised to target countries which charge tax on US imports by matching them with a reciprocal tariff.
Donald Trump has ordered his team to start calculating duties by early April – increasing fears of a global trade war that could also accelerate US inflation.
It is set to spark negotiations with dozens of countries aimed at lowering their tariffs and trade barriers. The US wants to shrink its goods trade deficit which topped $1.2trn (£954bn) last year.
A White House official said that countries with large US trade surpluses could be targeted first. The top five are China, Mexico, Vietnam, Ireland and Germany, according to the US Census Bureau.
The UK could be hit with tariffs as high as 24% if Mr Trump follows through on his threats to treat VAT as a tariff, according to Paul Ashworth, chief North America economist at Capital Economics.
Although some estimates are lower, he thinks Britain would be the fourth hardest hit, following India (29%), Brazil (28%) and the EU (25%).
This is based on VAT rates combined with existing tariffs, but the Trump administration also intends to take into account regulations, government subsidies, digital services taxation policies and exchange rate policies.
“Most people would consider VAT to be a non-discriminatory tax since it is also applied to domestically-produced goods making a level playing field,” said Mr Ashworth.
But the US still argues that VAT is a form of discriminatory tariff because America applies a much lower average sales tax at state level.
On Thursday, Mr Trump also held a meeting with Indian Prime Minister Narendra Modi, agreeing to join forces on artificial intelligence, semiconductors and strategic minerals.
During a news conference afterwards, Mr Trump said India has been “very strong on tariffs” and “it’s very hard to sell into India”, adding: “They’re going to be purchasing a lot of our oil and gas.”
India’s tariff rates are the highest, according to the World Trade Organisation, with a simple average 17% rate for all products compared to 3.3% for the US.