Schools have come under fire for sitting on millions of pounds that could help improve education standards.
The county's schools are now said to have a total of £14m in bank accounts, with balances far exceeding Government guidelines.
County Hall this week sent out the message that it was time to spend some of the money to bring about improvements for "today's children".
After receiving the latest update on balances from its 290 schools, the authority has decided to ask schools to justify their positions.
Schools unable to explain the size of their balances will be required to send their headteachers and chairmen of governors to meet the council.
Michael Waine, cabinet member for schools improvement, said: "At a time when we are working very hard indeed to raise standards in Oxfordshire schools, I was very surprised to see that such an amount of money had accumulated in the combined financial balances of our schools - an increase of £6m over last year.
"It is sensible for all organisations to keep some money in the bank as a contingency should any emergency arise.
"That is common practice. We do also completely understand that there are good reasons for some of this accumulated money - like late grant arrival, implementing a large IT project over two years and curriculum protection.
"However, we believe the present sum of money to be too high and we want schools to spend that on improving the education of children in Oxfordshire now.
"The county council is on hand to help and advise about that process whenever needed. We are in no doubt that this must happen sooner rather than later.
"We aren't encouraging schools to become spendthrift, but we are encouraging them to invest in our children more than they are at present."
Schools in England now manage their own budgets, allocated to them by the Government. The county council only administers the way the money is passed on.
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