Säpo came under fire recently after revelations in the Dagens Nyheter (DN) daily that some 5.3 million kronor ($802,500) were spent on a lavish James Bond-themed party.
Ask has now decided to agree to classify all details of Säpo's expenses, from the amount spent on coffee to premises rental to telephone surveillance, the newspaper reported on Sunday.
The government has explained the decision by claiming that national security is at risk if the information is made public, DN reported.
Further revelations regarding Säpo's expenses which emerged over the summer included an application for almost one million kronor back in value added tax (moms).
The claim was noticed by the Swedish National Audit Office (Riksrevisionen) in February and the Security Service later repaid 114,500 kronor.
The Security Service announced at the end of August that it would be making major staff cuts due to "financial strain". Around 100 jobs will be cut over the coming three years.
It was in connection with a request for documents pertaining to the planned cuts that Dagens Nyheter was told that all of Säpo's expenses, which amount to around one billion kronor per annum, were classified.
The decision has been confirmed by Beatrice Ask and can not be appealed, the newspaper reported.