The federal opposition hopes that the Remuneration Tribunal will agree to ''transitional arrangements'' to ensure that none of its shadow ministers have to miss out on hefty pay rises.

The Federal Parliament this week passed a law which will clear the way for the Remuneration Tribunal to proceed with plans to lift the salaries of MPs and senators, including boosting the pay of backbenchers from $140,000 to $185,000.

The tribunal also wants to recognise the additional responsibilities accepted by shadow ministers by paying them more than backbench MPs.

The tribunal proposed in an initial report last year that Opposition Manager of Business in the House of Representative Christopher Pyne be paid 27.5 per cent more than a backbencher.

Shadow cabinet members would get an additional 25 per cent and junior shadow ministers would get 20 per cent more than a backbencher.

But the tribunal said that the number of opposition frontbenchers receiving the extra pay could not exceed the number of ministers in the government.

Before the resignation of Kevin Rudd as foreign minister, the government had 30 ministers while the opposition had 32 shadow ministers.

The Coalition is expected to ask the tribunal to approve transitional arrangements to ensure that all 32 opposition frontbenchers receive the pay loadings.

The tribunal proposed increasing Prime Minister Julia Gillard's pay by $115,000 to $481,000. Mr Abbott's pay would rise by $81,500 to $342,000.

Parliament passed a bill designed to ensure that retired MPs and senators did not receive a ''windfall'' pension increase as a result of the pay rises.

The bill would also limit the number of free return Gold Pass rail and air trips taken by former members and their spouses to a maximum of 10 each year. Future MPs and senators would not be eligible for the scheme when they retire.

The tribunal had been delaying making a final determination on the pay increases until the bill was passed and signed into law.

The Association of Former Members of Parliament of Australia has warned that retired MPs and senators could challenge the law in the High Court.

Australian Greens Senator Lee Rhiannon said the pay increases proposed for politicians were excessive and a system should be introduced to ensure that they only received modest increases in remuneration.