The lender, part of Lloyds Banking Group, said customers using a smartphone, table or desktop computer would be able to receive a lending decision in less than 15 minutes.

An agreement in principle means a borrower has been accepted for a mortgage, but final agreement depends on issues such as a valuation report and confirmation of employment.

Halifax said it had created the tool to make sure customers understand how much they can borrow. It said this would aid their property search and allow them to act quickly when they find a suitable home.

The lending decision is made solely on information relating to the customer, meaning users do not have to input property details or values.

Instead, would-be homebuyers must enter information about their circumstances, income and commitments before receiving a lending decision. The decision can be shared with family members or estate agents.

Information about stamp duty costs and legal fees are also displayed to the customer, the bank said.

Craig McKinlay, mortgages director at Halifax, said the change would benefit people looking to buy a home quickly.

“The launch of this new instant agreement in principle (AIP) tool significantly reduces the amount of time a customer will need to spend to obtain a lending decision from Halifax,” he said.

“Being able to complete the application while on the move on both mobiles and tablets helps our customers fit the process around a hectic schedule. We are continually exploring ways in which we can serve our customers in the way that best appeals to their needs and this new offering further cements our reputation as the bank who gives our customers extra.”