The Daily Mail says United are ready to sign Ighalo for up to £15million this summer after it emerged the Nigerian striker's loan runs out on May 31.
Ighalo's temporary move from Shanghai Shenhua is set to end a month earlier than most loan deals.
United may have to negotiate an extension with the Chinese club if the Premier League season — on hold until the end of April —continues into June, although world players' union FIFPro is working on a solution to the contract uncertainty caused by the coronavirus crisis.
Either way, there is already a willingness at Old Trafford to sign Ighalo permanently after the former Watford striker scored four goals in his first eight matches.
Shanghai are prepared to sell Ighalo and have put a £15m valuation on the player, who will be 31 in June. They did not ask for a loan fee in January because United agreed to contribute £130,000 a week towards Ighalo's wages of £300,000 a week.