Brighton and Sussex University Hospitals trust chief executive Peter Coles is leaving to take up a secondment at the Department of Health.
Mr Coles will lead a national support team for trusts facing managerial and financial challenges.
Duncan Selbie will replace him as chief executive from 9 July. Mr Selbie is on secondment from the DoH, where he has spent the last four years as director general responsible for leading the delivery of national priorities and financial balance in the NHS in England.
A DoH turnaround team was sent into the trust last year to tackle a£17.3m deficit. The trust is aiming to break even by October this year.