Following a freedom of information request by the firm, it was found that 246 professional footballers were under investigation by the authority during 2019/2020, up from 87 the previous year.
In addition, the number of investigations of agents and paid fees rose to 55 in the period, up from the 23 recorded in 2018/19. A further 25 investigations were opened into football clubs during the same period.
Additional tax collected from the probes totalled £73.1m in the year ended 31 March, 2020, more than double the £35.3m collected the year before.
According to UHY Hacker Young, investigations have included probes into potential breaches of image rights deals, when players are paid additional money for the use of their image, particularly for advertising or endorsements.
Income from these deals can be paid to a company set up by the player for this purpose alone, and is only taxed at the 19% corporation tax rate, instead of the 45% income tax rate paid by high earners.
Elliot Buss, partner at UHY Hacker Young and a specialist in sports tax affairs, said: “If you are second-choice left-back in the Championship getting paid a great deal in image rights payments, then this is likely to trigger an investigation by the taxman.
“You may have to make a robust argument to HMRC to show how the value of the image rights has been arrived at.”
He added: “Despite having a very substantial income, many young footballers don’t get the advice they need when it comes to tax.
“Often they don’t realise they need to pay tax on the fees that the club pays the agent on behalf of the player when they sign a new contract. That frequently results in errors, investigations and hefty penalties.”