ING Direct savers in the UK will be protected by the British Government, instead of the Dutch compensation scheme, once a proposed buy-out by Barclays goes ahead.
Meanwhile, there is uncertainty for ING mortgage customers as Barclays has yet to determine whether it will change the rates they pay.
Barclays today announced it will buy the Dutch bank's UK savings and mortgages business, which will see 1.5 million customers transfer over.
The deal is expected to complete in spring next year, subject to regulators approving it, although the transferring of customers could take up to two years.
The safety shake-up will be a relief to many savers as the fear has always been that if an overseas bank went bust, its government would be more likely to protect its own citizens first.
When Icesave went bust in 2008, Iceland's government failed to protect savers with a UK-regulated account, though the UK Government stepped in.
Until completion, nothing will change for ING Direct UK customers. Here's how the move will affect you once the buy-out is complete.
Savings safety shake-up
Savings held with ING Direct UK are not currently protected by the UK's Financial Services Compensation Scheme (FSCS), which guarantees you'd get back up to £85,000 per person, per financial institution if the bank went bust.
Instead, ING Direct UK customers are protected for up to Ä100,000 (£81,000) by the Dutch government.
But Barclays' savings customers are covered by the FSCS, so following the acquisition, ING Direct UK customers will be covered by the FSCS scheme.
However this will be a shared protection with Barclays. So, if you have savings with both ING Direct UK and Barclays now, and you have similar balances on completion, both accounts will be protected together, for up to £85,000.
Martin Lewis, MoneySavingExpert.com founder, says: "In terms of protection this is both good and bad news.
"It's always been a risk saving with ING Direct UK. In the unlikely event it goes bust, you're reliant on a foreign government to bail you out. But that'll change.
"However, for those who already have savings with both Barclays and ING Direct UK, the shared protection means you've less cover. If the buy-out pushes you over the limit, spread cash elsewhere."
Will savings rates change?
Regardless of the provider, variable rate accounts are always subject to change so they could move up or down once controlled by Barclays but the same could similarly happen now.
ING says all guaranteed rates, such as fixed rate, will remain unchanged.
Mortgage question mark
Once the sale is complete, customers will owe their money to Barclays, instead of to ING Direct UK.
But Barclays has yet to finalise policy on rates, so there is a chance of hikes.
The most definitive it can say is customers "are expected" to get at least equivalent terms to those from ING.
ING Direct UK has also advised customers to make sure that the bank has users' most up to date mailing addresses, as it will be sending full details of the transfer and what it means via post in the next few weeks.