Chelsea have the option to sign Radamel Falcao permanently this summer for £37.8m, according to a transfer document published on the Football Leaks website.
The contract in question relates to the season-long loan transfer of the Colombian from Monaco in July 2015 and reveals that the Blues did not pay a transfer fee to the Ligue 1 side as part of the deal.
The Premier League outfit have an exclusive option to make the deal permanent this July but will have to pay €50m (£37.8m) in two equal instalments of £18.9m and have to make their decision by April 29.
Falcao has failed to feature for Chelsea since he was brought on for the final throes of their 3-1 defeat to Liverpool at Stamford Bridge in October.