New figures show there is almost $18 billion in lost and unclaimed superannuation accounts held by super funds or the ATO.

Australian Taxation Office (ATO) assistant tax commissioner Debbie Rawlings says the ATO has reunited $8.12 billion worth of accounts in the past four financial years.

She says Australians should check their super through the ATO's online services on myGov to see if they are missing out.

New figures show super funds are holding $14.12 billion of lost super, while the ATO is holding a further $3.75 billion.

People often lose contact with previous super funds when they change jobs, move house, or fail to update their details.

The Association of Superannuation Funds of Australia (ASFA) lobby says the law should be changed so that the tax commissioner it more active in reuniting lost funds with active accounts.

The ASFA says that because the tax office holds tax file numbers and other identifying information, it is the logical choice for the commissioner to match lost accounts.

“A move to place the responsibility on the ATO to reunite lost accounts with their true owners would be welcomed by consumers,” ASFA chief policy officer Glen McCrea said in a statement.