Exit fees charged to people trying to close unwanted superannuation accounts have been banned in a suite of new budget measures aimed at protecting retirement incomes.

People who have failed to keep track of their superannuation will also benefit from a new cap on some fees and new tax office capabilities that will allow them to be automatically reunited with lost or inactive accounts.

The federal government will cap passive fees on accounts with balances below $6,000 at three per cent from July 1, 2019, and all exit fees will be banned.

The Australian Taxation Office is also getting more power to gain control of inactive super accounts with balances below $6,000, allowing it to combine the lost funds with a person's active account.

This will send an estimated $6 billion of super back to 3 million Australians in 2019/20.

Insurance arrangements within superannuation are also changing, giving young people or those who have not contributed to their super for more than a year the chance to opt out of premiums charged for policies they sometimes do not want or even know about.

The government says this measure will help protect the retirement savings of young people and those with low balances by ensuring their super is not eroded by premiums.

Treasury estimates the new super measures will deliver a benefit of $864 million to the budget over the next four years.