[caf]

This does depend on where you live. In some places, mortgages are offered with "offset accounts", where your positive balance in the account offsets your outstanding debt on the mortgage, and in doing so reduces the interest accruing on the loan. This means that your excess funds effectively earn the mortgage rate of interest (and since interest avoided isn't "income", this isn't taxed as deposit interest would be either), so it's an attractive option if you have a mortgage.

[DJN]

That sounds really interesting. Can you provide a link to an example or source of additional info.

Thanks

[wintersFright]

offset accounts are common in Australia http://www.news.com.au/money/banking/offset-accounts-help-lo...

[caf]

Likely anywhere that variable-rate/variable-term mortgages are common (ie. partially funded by short-term securities).

[seanmcdirmid]

Sounds similar to America's interest exemption.