Banks and building societies have been accused of not doing enough to reunite customers with the millions of pounds lying unclaimed in dormant accounts.

The Treasury plans to seize cash in forgotten accounts to set up a national network of sports and arts centres. It is likely to be 2009 before the cash is grabbed and the government has urged financial institutions to launch a big push to reunite savers with their money.

But John McFall, chairman of the Treasury committee investigating unclaimed assets, denounced banks and building societies last week for failing to do enough to inform customers about the unclaimed cash.

Halifax has been the only bank to launch a campaign to find the rightful owners of the £44m in its dormant accounts.

The government wants to get its hands on money in accounts that have been left untouched for 15 years or more. With fixed-term accounts, the 15 years begins at the end of the fixed term. Cash Isas will be included in the raid.

More than £300m is thought to be lying unused in such accounts. People often lose track of savings because they fail to pass on their new address when they move house.

Other account holders have died leaving their heirs unaware of their accounts or even that they can claim money.

Given the lack of action by the banks and building societies, consumers are being urged to double-check whether they have missing money to reclaim. Here we explain how.

I think I have money in an account I haven’t touched for 15 years. How do I reclaim my savings?

If you find a passbook for an old savings account you have forgotten about, take it to a branch of the relevant bank or building society. If your address has changed you will need to take proof of your current address, such as a utility bill.

If you can’t remember the specific bank or building society, contact the British Bankers’ Association at bba.org.uk (020 7216 8909) or the Building Societies Association at bsa.org.uk (020 7437 0655).

And if the money belongs to a relative who has died?

If you find account details while sorting out the paperwork of a dead family member, you need to take a copy of the statutory declaration or probate form when you claim the money.

Can I still reclaim money when the scheme is running?

The proposals include a promise that customers will be able to reclaim cash, plus interest, if they discover money in an account has been given to charity – even after 15 years.

Will any accounts be exempt?

Accounts that belong to savers who die without making a will, and with no known kin, continue to pass to the state.

Customers with a “no mail” account where they have asked not to be contacted by the bank or building society, will not have their accounts raided as it is difficult to determine whether they are dormant.

How do I find other ‘lost’ assets?

For lost NS&I bonds, certificates or accounts try nsandi.com (0845 964 5000). For a lost pension, go to thepensionservice.gov.uk (0845 600 2537). For insurance policies, try the Association of British Insurers at abi.org.uk (020 7600 3333) or for unit trusts the Investment Management Association at 020 7831 0898 or investmentfunds.org.uk.

If details are sketchy, the Unclaimed Assets Register charges £18 a search. Visit uar.co.uk (0870 241 1713).