"Whistletree will provide a secure, long-term home for these mortgages and loans based in the UK."
Whistletree has been purpose-built for Northern Rock products and the terms and conditions of the existing loan agreements will remain unchanged.
Customers transferring to Whistletree are being informed by letter this week with full details of what action, if any, they need to take.
The initial purchase of the portfolio from Cerberus Capital Management was announced in November 2015.
Padraig Carton, Customer Service Operations Director, said: “We are delighted to welcome these customers to Whistletree from today. Whistletree will provide a secure, long-term home for these mortgages and loans based in the UK.
“Supporting hardworking people and helping local communities right across Britain to thrive is absolutely at the heart of what TSB was set up to do. Whistletree is a natural extension of this.”
