Wolverhampton's New Cross Hospital and Royal Stoke University Hospital are among those which will have to be paid to take patients who would otherwise go to Princess Royal Hospital.
It is part of the internal market of the NHS, where trusts pay each other for services when needed.
It comes as Shropshire Clinical Commissioning Group's board was told that Shrewsbury and Telford NHS Hospital Trust could face a loss of £3.5 million if the PRH night-time closure goes ahead in mid-November.
The accountable officer at Shropshire CCG said there was an obligation to pay other trusts if patients choose to leave the county for treatment.
Simon Freeman said: "As a CCG we are responsible for paying for hospital visits, admissions and operations for all patients registered with one of our 41 GP practices.
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"This responsibility extends to where our patients choose to attend hospitals outside our county such as Wolverhampton or Stoke. the overnight closure of the A&E at SaTH agreed by the trust board would need to see some patients taken out of county for their treatment.
"This would require us to pay those providers for our patients care. Clearly in this circumstance SATH would lose the income for these patients which by their estimates amount to £3.5m a year. Shropshire CCG would of course spend the same amount of money with different providers."
Shrewsbury and Telford Hospital NHS Trust (SaTH) has voted to press ahead with the department's closure, a decision which has sparked major concern and a petition being signed by almost 20,000 people.
It has been said that the department will be closed overnight from 8pm to 8am for at least six months.
Concerns were raised at Shropshire CCG's board meeting on Wednesday about the mid-November closure date.
Members said there were many decisions to make in a short period of time.
It was also said that The Royal Wolverhampton NHS Trust does have the capacity to see Shropshire patients, but not to send doctors to Shropshire.