The rates are discounted from the Society’s standard variable mortgage rate until 31 May 2015.
The Society will only consider applicants for its buy-to-let product range if the landlord has no more than three buy-to-let properties in total.
Val Peacock, Darlington district manager based at the Society’s Tubwell Row branch, said: “We only launched these new products a few days ago and we have been pleasantly surprised by the initial interest and demand.
“This clearly demonstrates both the buoyancy in the buy-to-let market and the attractiveness of our new products themselves. Tranche sizes are however limited so I would encourage anyone interested in applying for these mortgages to contact us without delay.”