Members of the armed forces redeployed within the UK can now rent out their homes without facing higher costs or having to change their mortgage.
Defence minister Mark Lancaster said it would mean servicemen and women saving time and money "when they are fulfilling vital roles across the country".
Members of the military who wanted to rent their homes out during deployment used to have to change their residential mortgage to a buy-to-let one, often being hit with new charges and an increased rate of interest.
However, the new agreement under the Government's armed forces covenant means they can now go ahead and rent their homes out without having to jump through these hoops.
Mr Lancaster said: "Our armed forces keep us safe and rightly we should be making sure they're fully supported.
"This extension means our brave men and women will save time and money when they are fulfilling vital roles across the country, and is another example of how the covenant is making a real difference."
This commitment from the majority of the UK's high street banks and building societies follows a similar deal for personnel posted abroad, which was agreed in January.
The initiative is supported by 47 of the UK's largest banks and building societies, including Barclays, HSBC and Nationwide.
The changes are set to benefit almost 265,000 people in the UK and overseas.
British Bankers' Association chief executive Anthony Browne said: "Members of our armed forces work all over the world to look after us, so it's only right that we look after them."
The armed forces covenant has also seen more than 9,000 personnel benefiting from the military's own help-to-buy scheme, and 86% of the UK's motor insurance industry commit to waive cancellation fees and preserve no claims discounts for up to three years when personnel and their families are posted abroad.