The England international is presently on loan with Aston Villa. The Midlands outfit have an option to buy him for £40 million.
However, the package is unlikely to be triggered. Rashford seems determined to join Barcelona after missing out last winter.
The player's agents are already discussing personal terms with the Blaugrana ahead of a potential transfer at the end of the season.
United are likely to accept a lesser package in the summer and it is claimed that Rashford could be sold for a fee of £30m.
Rashford fell out-of-favour under manager Ruben Amorim in December last year and he has no plans to play under him.
The attacker has a long-term dream of playing for the Blaugrana. A transfer could materialise in the next transfer window.
A deal will depend on the forward accepting a huge pay-cut.