The mutual will pay a 0.2% fee to brokers on its approved panel of intermediaries for all existing customers transferring onto a new product.
Newbury Building Society sales manager Karen Smith said: “We have always valued the support and hard work of our intermediary partners and would like to thank them for their business.
“We are pleased to announce our intent to pay a procuration fee for retention business later in 2018. We will be confirming an exact date for launch nearer the time.”
The building society is the 16th biggest building society in the country and completed around £200m of lending in 2016, according to the most recent figures available from UK Finance.