HBOS will call on Callcredit's range of marketing datasets and analytical support for its cards marketing acquisition programme.
Caroline Worboys, managing director of Callcredit Marketing Solutions, said: "This success is a testament to the quality, breadth and depth of the data assets now provided by Callcredit.
"The decision for Halifax and Bank of Scotland, alongside other UK lenders, to use our services shows that our datasets are mature, robust and of real value to the lending sector."
Deby Herring, head of retail and targeted channels for Halifax and Bank of Scotland cards, said: "After carrying out a thorough review of our marketing data strategy it was evident we needed the support of a flexible and proactive supplier.
"We are therefore delighted to now be working with Callcredit."