Excess itc claimed in2017-18

I think interest is applicable when SCN is issued, u don't pay in given time. assessment is not done yet and u hv self declared ur default , so less chances for the same.

Yes interest is applicable @ 24% even though the same being not utilised , but as per Section 41 of CGST Act the eligible ITC only can be credited to ECL. & moreover , Section 50(3) of CGST Act stating The interest applicable the person makes undue or Excess claim of ITC.
Hence , Interest is applicable