The property near Hartley Witney was originally due to open in April 2012 but has suffered numerous delays since.
Last year a spokesperson for Heckfield Place said it would "definitely" be opening in spring 2015, although she was unable to confirm the exact date.
Now the hotel's website states it will be opening in 2016, but still no specific date has been given.
A spokesperson for the property said: "Heckfield Place is undergoing a meticulous programme of restoration and refurbishment transforming the property into an idyllic country retreat.
"The standard of the redevelopment has been incredibly high, with each tile, tap and rug handpicked by Heckfield Place's design team. This extraordinary level of detail cannot be hurried."
The Grade II-listed country house, once used as a training centre and wedding venue, is owned by private investment company Morningside Ventures.
Appointments since the hotel was first announced in early 2011 have included general manager Charles Oak, who joined from the May Fair hotel, London, and chef Chris Staines, from Foliage restaurant at the Mandarin Oriental hotel, London.
But years of construction delays resulted in them both leaving before the hotel ever had a guest come through its doors.
Char and Henry Gray are now the general managers at Heckfield Place having been appointed in 2014. The couple has more than 60 years' experience in the hospitality industry between them.
They have worked as co-general managers in several hotels and resorts throughout the world, including international luxury hotel group Amanresorts.
Heckfield Place appointed Barnaby Jones as executive chef in 2014.
Once open, the multi-million pound renovation of the property is expected to include 46 individually designed bedrooms and suites, three restaurants, a cinema, a wine cellar and three spa suites.
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