The Premier League giants have an agreement in place with Barcelona for an initial fee of €65m and the two clubs have been holding talks over the structure of the payment and the potential €20m add-ons.
Manchester United were hoping to sort out the signing of De Jong before they fly out to Thailand on Friday for their pre-season, but are unlikely to be able to.
And it emerged on Wednesday night that Barcelona owe around €20m to De Jong due to the wage cuts he agreed to in the previous seasons.
The Dutchman’s camp want Barcelona to clear their dues before he agrees to leave the Nou Camp this summer.
Manchester United and Barcelona are now together trying to find a resolution to the issue that is stalling the deal.
The Red Devils remain confident that De Jong will become a Manchester United player this season and he remains Erik ten Hag’s top target.
However, Manchester United also accept that they need to be patient given the complicated nature of the issue of the midfielder’s outstanding payments.
