Carlisle have asked Watford for the details of Danny Graham's £3.5million move to Swansea due to a clause which may be involved in the deal.
The Brunton Park club are entitled to £450,000 due to a sell-on clause but could also benefit from any future transfers involving their former striker.
"This affects us now, and our cash flow for probably the next four years," managing director John Nixon told the News & Star.
"We have sent an issue to Watford to say we need to know the deal. We have got a right to know.
"Within that deal (Watford) might have got a sell-on themselves of something like 20%. That means we would get 15% of 20% should he move on again.
"You have to keep an eye on these things."