Dozens of players in each division will see their offers expire on June 30, but the national season won’t be over by then.
FIFA has announced plans to extend the June 30 deadline to the end of the season, but sports lawyers say it will not be as simple as that.
Boro, like all clubs, is watching developments closely. Seven senior players are out of contracts at Riverside this summer and face an uncertain future as it stands.
By the end of June, several players from the first two divisions will sign new agreements with their clubs.
But as it stands, there are 57 senior team professionals who will be out on contract in the Premier League this summer.
Obviously, many players are unrealistic targets for championship clubs. But should some of the ones listed below be of realistic interest to Boro this summer?
Arsenal – No
Aston Villa – Borja Baston, Keinan Davis
Bournemouth – Ryan Fraser, Jordon Ibe, Charlie Daniels, Andrew Surman, Simon Francis, Artur Boruc, Brad Smith
Brighton – Beram Kayal, Ezequiel Schelotto
Burnley – Aaron Lennon, Jeff Hendrick, Joe Hart, Phil Bardsley, Adam Legzdins
Chelsea – Pedro, William, Olivier Giroud, Willy Caballero
Crystal palace – Stephen Henderson
Everon – Oumar Niasse, Leighton Baines, Cuco Martina, Maarten Stekelenburg
Leicester – Nampalys Mendy, Christian Fuchs, Wes Morgan, Eldin Jakupovic
Liverpool – Adam Lallana, Nathaniel Clyne, Andy Lonergan
Manchester City – David Silva, Claudio Bravo
Manchester United – No
Newcastle – Javier Manquillo, Matty Longstaff, Andy Carroll, Jack Colback, Rob Elliot, Jamie Sterry
Norwich – No
Sheffield United – Ricky Holmes, Leon Clarke, John Lumdstram, Jack Rodwell, Phil Jagielka
Southampton – Shane Long
Tottenham – Jan Vertonghen, Michel Vorm
Watford – Adrian Mariappa, Ben Foster, Heurelho Gomes, Jose Holebas
West ham – Carlos Sanchez, Pablo Zabaleta
wolves – John Ruddy, Bright Enobakhare, Phil Ofosu-Ayeh