The 27-year-old defender left Leeds to join the Bundesliga club on loan in the last summer transfer window.
Leeds’ relegation from the Premier League meant that a clause in his contract allowed him to leave on loan as long as a club were prepared to pay his full wages.
The centre-back has started their opening three Bundesliga clubs and is one of their most important players in the squad.
And according to German daily Tageszeitung, Koch is also one of the top earners in the Eintracht Frankfurt squad.
He is drawing a salary worth €3m per year, which places him as the third or fourth-highest-earning member of their squad.
Koch was earning the same at Leeds and Eintracht Frankfurt are happy to pay that figure given his Premier League experience.
Eintracht Frankfurt are expected to sign Koch on a permanent basis next summer when his contract at Leeds expires.
