Former Coalition minister Philip Ruddock has been "double dipping" by receiving a parliamentary pension of more than $200,000 a year on top of full pay for his new role as Australia's human rights representative.

In Senate estimates hearings on Thursday, Labor senator Penny Wong asked Department of Foreign Affairs and Trade officials to explain how much the Liberal Party elder and former immigration minister was being paid for serving as the government's special envoy for human rights.

After 42 years in federal Parliament, Mr Ruddock is entitled to an annual pension of about $215,000 per year, or a lump sum payment of about $2.15 million plus $107,500 per year.

He is also being paid for his new departmental contract, a per diem share of between $210,482 and $241,715, in line with a senior public service SES band 2 role. Mr Ruddock is only paid for days worked.