Santander has extended its assured short hold tenancy policy from 12 to 36 months, saying it wanted to support both tenants and landlords.
The lender said tenants had been impacted by the existing policy, which enables landlords to increase rent after six months of a tenancy.
The lender stated it wanted to enable renters to better budget, while giving security to landlords.
Miguel Sard, director of mortgages at Santander, said: "We hope these changes in policy will go some way to helping people budget and potentially save towards a deposit for their own property, supporting the first-time buyer market and enabling social mobility, while also helping to prevent the risk of homelessness.
"Meanwhile, it also ensures landlords have a guaranteed rental income and don't have to worry about loss of income with an empty property."
Last month Santander introduced a soft credit check process across its intermediary business to ensure customers' credit ratings are not affected at the early stages of application.
Early last year the Spanish bank rescued its smaller rival Banco Popular from the brink of collapse.
The deal cost Santander 7bn euros (£6.1bn), which is believed to be about 2bn euros more than analysts had expected.