The 30-member JPC, set up in March 2011, will have the last hearing of witnesses next week when CBI Director Ranjit Sinha and Telecom Secretary R Chandrashekhar are expected to appear.
JPC Chairman P C Chacko on Tuesday said that next week onwards, focus would shift to writing of the draft report, leaving no scope for calling any more witnesses.
The CBI chief has been asked to sum up before the panel its probe on February 12. On the same evening, the JPC will hear Mr Chandrasekhar to corroborate the evidence gathered by the panel so far.
"We will wrap up evidence gathering and start preparing the draft of the report," Mr Chacko told reporters here.
He said the plan is to submit the report to Parliament by March 31 so that it could be discussed during the second half of the Budget session.
BJP members had been demanding summoning of Mr Chidambaram before the JPC as he was the Finance Minister when the controversial 2G spectrum was allocated in 2008.
BJP members had even boycotted the JPC proceedings after their demand to call Prime Minister Manmohan Singh was shot down by Mr Chacko.
Mr Chacko had maintained that the demand to call Chidambaram could be met only if the committee had a unanimous opinion.
Congress members have been strongly opposing calling of Mr Chidambaram or the Prime Minister.
A Minister can be called by any parliamentary committee only after a nod by Lok Sabha Speaker, who can take a call only when there is a unanimous decision by the panel.