Ulster hope to announce the signing of a new fly-half within the next week.
Australia back Christian Lealiifano, 30, who joined on a short-term contract in August, will leave the province after the final Champions Cup pool match against Wasps on 21 January.
Operations director Bryn Cunningham says Ulster should be able to announce a replacement for Lealiifano next week.
New Zealand's Stephen Donald and Australia's Quade Cooper have both been mentioned as possible targets.
"We do have plans and we'll be in a position, hopefully, next week to announce a replacement," said Cunningham.
"It is a very difficult time of the year to try and get a replacement of quality that is going to make a difference to our squad but I think we've done that."
Lealiifano has been in superb form for Ulster this season, making 15 appearances and scoring 47 points despite arriving just a week before the start of the season.
Ulster hope to recruit a similarly experienced player for the rest of the campaign.
"We've got someone there and we will make that announcement when it's all tidied up," said Director of Rugby Les Kiss.
"Christian has done his job for us. Johnny McPhillips came out and got another chance [against Leinster] and did a good job as a young fly-half and Christian has done well in helping him along the way.
"We need someone with a bit of experience and that's what we intend to do."
Kiss confirmed the new arrival will be an overseas player, which rules out a possible loan signing from a rival Irish province.