Kettering General Hospital says it expects to be £25.1m in debt by the end of March.
The hospital, like many NHS organisations, is currently in a financially challenging position.
In July chief executive David Sissling told the Northants Telegraph the predicted deficit for 2016/17 was £6.4m.
But the debt now looks set to be four times the original estimate.
Acting director of finance Nicci Briggs said: “Our transformation programme is comprehensively addressing our financial challenges but there remains a lot of work to do both at KGH – and in the wider health and social care community – to tackle north Northamptonshire’s operational and financial challenges.
“[For the] year to date our teams are currently exceeding their internal savings and productivity targets and we would like to thank them all for their hard work this winter.”
The hospital was put on black alert over Christmas and the new year, placing pressure on beds.
Between December 19 and January 1, some 3,318 people attended A&E – 14 per day (6.2 per cent) more than over the comparable period in 2015.
Mrs Briggs says this has undoubtedly had an impact on the hospital’s finances.
She said: “As you will be aware the NHS is experiencing a very challenging winter period where we have been dealing with record levels of emergency care demand – and this has had a clear financial impact.
“Going forward, through the county’s sustainability and transformation plan, we will be working very closely as a health community to address the many inter-related issues which affect health and social care finances.”
The hospital currently has a turnover of about £220m per year.
The trust has undergone a number of management changes recently with Mr Sissling on sick leave.
He was replaced by Clare Culpin who is now set to leave, with Fiona Rose appointed as interim chief executive.
Director of finance Kish Sidhu has also left the trust.