Rangers were able to register the signing of Calvin Bassey during a one-day opening of the transfer window last week.
The Light Blues announced early last month they had recruited the left-back, 20, from Leicester City on a pre-contract agreement.
But Bassey was not able to link up with his new club in pre-season training until the deal was formalised on 1 July.
Domestic football associations across Europe, including the English and Scottish FAs, were granted permission by FIFA to open the transfer window for one day.
Scottish, Premier League and EFL clubs were among those given the opportunity to register any pre-agreements and returns from international loans on 1 July.
The deal has allowed Rangers to register Bassey as well as Chelsea to register blockbuster signings like Timo Werner and Hakim Ziyech.
The Scottish window is likely to formally open at the end of July and then run until around 5/6 October in line with most European windows.
Rangers revealed on their social media channels last week that Bassey had arrived to train with his new teammates.
He had not been allowed to initially link up with Steven Gerrard’s squad for the start of pre-season training last month.
— Rangers Football Club (@RangersFC) July 3, 2020
Football Insider exclusively revealed on 6 June that Bassey was headed to Ibrox after rejecting a new contract at Leicester City.
Cross-border rules mean Rangers only need to pay Leicester a fee of around £300,000, avoiding the need to pay the same compensation for development costs as clubs down south.
In other Rangers news, there have been major new developments over the future of Alfredo Morelos at Ibrox.
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