The fee free offer, which is now available until the end of July, represents a saving of up to £999.
The banks launched the first-time buyers' offer in May and last month extended it to homeowners looking to remortgage or switch to a Clydesdale or Yorkshire Bank mortgage.
Steve Reid, retail director for Clydesdale and Yorkshire Banks, said: "The banks fee free mortgage offer is designed to help people find the right mortgage to suit their individual needs without having to pay an arrangement fee and we have had a great response to the offer so far.
"Now the offer has been extended until the end of July we anticipate an even greater uptake from buyers who want to take advantage of this saving."
Clydesdale and Yorkshire Banks offer a 3-year rate fixed at 5.99% for buyers with a 5% deposit and a 3-year fixed rate at 4.99% for buyers with a 10% deposit.
In addition, customers re-mortgaging from another lender won't have to pay any legal or valuation fees and may be interested in a 5-year deal fixed at 3.79% for a 65% loan-to-value mortgage.
