Tarbert, on Harris, will see its BoS branch close on February 22, while North Uist's Lochmaddy will shut up shop on February 26.
Customers wanting to visit a BoS in Lewis and Harris will now need to travel to Stornoway, 36.4 miles from Tarbert.
The closest BoS branch to Lochmaddy is 18.25 miles away in Balivanich, on Benbecula.
Currently BoS does not have a mobile bank service in the Western Isles.
Commenting on the closures, Alasdair Allan, the SNP MSP for Na h-Eileanan an Iar, said he was concerned about the closures as many services needed to be carried out in banking premises, which also avoid the technical issues of digital banking and lengthy waits on the phone to speak to customer service.
He also pointed out BoS's second alternative for Tarbert customers of travelling to Stornoway was a two-hour round-trip, and that its second alternative - a ferry to Skye - was incredible.
“After a taxpayer-funded bailout of £30 billion following 2008’s financial crash, surely the Bank of Scotland can do better than this for its customers, particularly a number of elderly or vulnerable users, for whom making the switch to online or over the phone banking could be extremely difficult," Mr Allan said.
BoS's review of the two closing branches states that 66 per cent of its Tarbert customers were over the age of 55, with the number being 62 per cent in Lochmaddy.
However, the review also found that only eight customers stated they had regularly used the Lochmaddy branch in the 12 months up to March 2023. In Tarbert, the number was 32.
The closures in the Outer Hebrides are two of 26 scheduled by the bank across Scotland.
In March BoS announced a 50 per cent profit decrease for 2022, to £1.1 billion. While it cut its staff costs by 4 per cent to £1.084 billion, its outgoings on premises and equipment rose £33 million to £173 million.
A list of all BoS's branch closures, alongside internal reviews conducted into the branches, can be found on the Bank of Scotland website.
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