The authority owns 12 of the 21 libraries it proposes to close and could bank the millions if campaign groups currently fighting to buy and save the libraries cannot find the funds.
The under-threat libraries which are owned by NCC are: Abington, Desborough, Earls Barton, Higham Ferrers, Irchester, Long Buckby, Middleton Cheney, Raunds, Roade, Rothwell, Thrapston and Wollaston.
A Freedom of Information request by campaigner Marion Collyer from Deanshanger library has revealed the value of the assets.
In an answer to an FOI question about how much NCC could make from each sale, the council’s reviewing officer Simon Deacon said: “Given the current expression of wish process, it is not currently possible for NCC to confirm how much it anticipates to raise from the sale of any of the above libraries.
“NCC has obtained an RICS Red Book Valuation of the Library Assets as part of the expression of wish process which indicates that those freehold libraries listed above have a cumulative freehold value of c£3,250,000.”
The Royal Institution of Chartered Surveyors (RICS) red book sets out professional standards for valuing assets.
Campaign groups are currently putting together business plans to try and make their case for taking over the libraries.
The county council announced last October that it was proposing to shut down the libraries as part of cost cutting measures.
The authority needs to make £35m savings this financial year plus find the £13m it took from reserves last year.
If all 21 libraries threatened close, only 15 will remain across the county.
The groups have until June 25 to get their bids into the county council but many of the groups have criticised the authority for asking for too much information from them and for pricing the future running of the libraries at too high a cost.
The authority is proposing a range of packages and offers that the independent libraries could take up, including advice at £100 per hour.
The sale of Irchester library has sparked controversy.
NCC obtained the library free of charge from the parish council in the 1960s when it took over the running.
It is now asking for £195,000 from the parish council to buy the library back.
The victorian library was built by philantrophist Andrew Carnegie on land gifted to the parish by local landowner Lady Wantage.
Irchester parish council clerk Nikki Daft said: “Nobody is telling us anything.
“We have written a letter to NCC but have had no response.
“It would not be so bad if we could sit down and negotiate with them.”
Kettering Council’s scrutiny committee will tomorrow (June 12) consider whether the Kettering authority should buy the freeholds of both Rothwell and Desborough libraries as part of its commercial property plans.
NCC is asking for £460,000 for Rothwell and £360,000 for Desborough.
A report by KBC executive director Martin Hammond states: “It is not clear what timetable the county council is working to on the transition, whether and when it will accept any proposals for community run library services and even if the library buildings are still for sale.
“Clarity has been sought from NCC but no definitive answers have yet been received.”
The scrutiny committee can decide to put the matter before Kettering Council’s executive committee to decide upon.
The meeting is taking place at Kettering Council offices in Bowling Green Road at 7pm.