The former Man of Steel is facing a long layoff after suffering a ruptured Achilles tendon in training last weekend.
Tigers are close to the salary cap, which under normal circumstances would restrict their ability to bring players in, but have been granted special dispensation by the Rugby Football League.
The governing body accepted Tigers’ request after being told Gale, who underwent surgery on Thursday, will be out of action for between nine and 12 months, potentially sidelining him for the entire 2019 campaign.
“It gives us the facility to bring someone in as and when a half-back becomes available,” said Castleford director of rugby Jon Wells.
“Our main concern is Luke and we would like him to take the opportunity to spend some quality time with his young family.”
Gale was already set to miss the opening month of the season after undergoing knee surgery.
He was unavailable for 15 matches last term after suffering a fractured kneecap in a home win over Wakefield Trinity in April.
Gale missed last year’s England Test series against the Kiwis and is unlikely to be available when Great Britain Lions tour New Zealand this autumn.
A spokesman for the RFL confirmed Castleford have been successful in their application to remove Gale’s salary from their 2019 cap.
However, if the player makes a quicker-than-expected recovery the club will need permission from the governing body to play him this year.
That situation arose in 2016 when Warrington forward Ben Harrison was initially ruled out for the season with a shoulder re-construction.
When the player recovered before the end of the season they sought permission to play him, but were denied and he ended up on loan at Wakefield Trinity.
Jamie Ellis, Ben Roberts and Cory Aston are all vying to partner stand-off Jake Trueman in Tigers’ Betfred Super League opener at home to Catalans Dragons on February 1.
Meanwhile, Tigers have been linked with Huddersfield Giants stand-off Jordan Rankin in a swap move also involving Castleford’s Joe Wardle.