Both players earn in excess of £300,000 per week, placing them among United's biggest financial commitments. Yet neither is currently delivering the consistency or influence the club needs, with their roles in the team increasingly under scrutiny.
Fernandes has been moved into different positions by Carrick as United attempt to find a formula that brings greater control and attacking threat. Rashford, meanwhile, has started the past two Premier League matches on the substitutes' bench, raising further questions about his place in the manager's plans.
United face Como in the Champions League on Wednesday, looking for a morale-boosting win.
But sources indicate that the futures of both players will come into focus in 2027, particularly if United's performances and results fail to improve.
Rashford's contract runs to 2028 while Fernandes sees his deal expire in 2027, although there is an option for an extra year. Their salaries make it difficult for the club to carry players who are not consistently delivering the level of contribution expected.
United are not in a position to overlook the financial implications of their squad decisions. With pressure to manage costs while building a team capable of challenging at the top end of the Premier League, the balance between wages, performance and long-term planning is important.
There is also a risk that frustration could grow internally if the current situation continues, while Carrick himself is also under pressure as the wider picture has to be assessed.
United's results have added urgency to the debate, as they are averaging just one point per game and currently look a long way from securing Champions League qualification - a scenario that would carry significant financial consequences as well as undermine the club's sporting objectives.
Missing out on Europe's elite competition would make the need for difficult decisions even more pressing. United would have less room for error in the transfer market and greater incentive to ensure their wage bill reflects the contribution they are receiving.