More than 7,000 Nationwide Building Society customers opened Help to Buy Isa accounts in the first week.
Some have already applied for Nationwide’s Save to Buy mortgages, available for completion on mortgages from 1 February 2016.
Two thirds of prospective homebuyers are expected to take advantage of the new Help to Buy Isa even though interest rates so far have been disappointing.
Nationwide pays a savings rate of 2% and offers mortgage cashbacks of up to £1,750, on top of the Government Help to Buy bonus of up to £3,000 per person.
The society claims to be the only large provider offering more than one cash Isa product in its wrapper.
This means that if a customer who saves the monthly maximum in a Nationwide Help to Buy Isa and a Nationwide main Flex current account will have £1,607 in their accounts from 1 February 2016.
This will make them eligible for a Government bonus of £400.
Savers will also be eligible to apply for a range of cashbacks.
These include the Nationwide Save to Buy cashback of £500, Nationwide’s First Time Buyer cashback of £500, and its £250 Flex mortgage cashback.
This makes a total of £1,250 in Nationwide mortgage cashbacks.
With the £400 Help to Buy bonus, the total potential benefits package from 1 February is £1,650.
Nationwide’s Help to Buy ISA customers will be offered access to the its Save to Buy mortgage range, available for those with a 5% to 14.99% deposit.