The lender said it believed this change would be beneficial for customers as it would “give them more time to complete their product transfer and the opportunity to secure their new mortgage rate sooner”.
Natwest said the change also applied to its Metro to Natwest customers.
For customers whose deals were due to expire in December, their product transfer roll off window will now be 1 July.
Deals that were due to expire in January next year product transfer roll off window will start from 2 August, and for deals due to end in February next year the window will open from 1 September.
The product transfer window for deals ending in March, customers can start the product transfer process from 1 October.
The lender added that customers whose product ended in November would also be eligible to switch from 1 July.
Natwest said that if the date fell on a Monday, Sunday or bank holiday then the roll off window would start from Tuesday.
Luke Christodoulides, national account manager said: “We’ve made great strides this year to improve our product transfer proposition, so that we have a streamlined process that enables our broker’s customers to switch easily.
“In the current climate of increasing interest rates and uncertainty around cost of living we are pleased to be able to support our customers, to enable them to secure their new mortgage rate far earlier.”