Should a non-profit organization which used FCF model in FP6 use a fixed overhead rate of 20% in FP7? If not, can it use the overhead rate of 60%?

If the organisation has an analytical accounting system then they have to go for either their real indirect costs or the 20% flat-rate.

If the organisation does not have an analytical accounting system then it can choose the 60% derogation model if it wishes to.