It claims the UK is one of only three of the 43 most advanced economies where the cost of tax collection is not falling.
The IEA called for radical tax reforms it says could reduce costs by a third, including the abolition of special tax relief on company investment.
Mark Littlewood, director general of the IEA blames the UK's long tax code, which runs up to 8,300 pages of primary legislation, compared with 1,700 in Germany and 1,300 in France.
He said: "Often debate focuses on the overall level of taxation – but this report clearly shows that merely complying with tax laws is an enormous burden on British business.
"Not only do we need to slash tax, we need to simplify it to allow enterprise to thrive."