Town have given George O'Callaghan, Matt Richards and Sammy Moore permission to play for their loan clubs in this Saturday's FA Cup first round. O'Callaghan and Richards are with Brighton, who take on Cheltenham, while Moore is with Brentford, who face Luton.
Jim Magilton's decision to allow the trio to play for their temporary clubs suggests that none of them are likely to come into his plans when they return to Portman Road in January.
The Blues have not commented on whether defender Ian Miller, also on loan until January, will be allowed to play for Darlington at home to Northampton, which suggests permission has not been given.
Earlier in the season, Jordan Rhodes was allowed to play for Oxford in the qualifying stages of the trophy, the striker scoring twice in a 2-1 victory over Merthyr Tydfil. The 17-year-old returned to the club earlier in the week at the end of his month at the Kassam Stadium.