Experts say the value of the bank's assets have decreased significantly.
The size of its capital hole will help determine the extent of debt 'haircuts' that its creditors face.
Its top executive told Austrian radio that there was no other way to deal with that gap other than a debt haircut.
“Our job is to sell our assets – the collateral as well as the loans, most of which are non-performing – as well as we can,” Chief Executive Officer Sebastian Schönaich-Carolath told Oe1 radio on Thursday, when asked if a debt cut was needed.
The finance ministry says it will negotiate with the bank's creditors over debt reduction so that taxpayers don't have to cover the losses.
Hypo Alpe nearly collapsed over bad loans in the former Yugoslavia.
After €5.5 billion of state aid and growing public discontent, Austria’s government halted further support in March.
Heta is the first European bank to be wound down under the EU’s Bank Recovery and Resolution Directive, a new law designed to protect taxpayers from the cost of bank failures.
The main investors in Heta’s bonds are German state-owned banks, mortgage banks and insurers.