Alliance & Leicester is linking with Legal & General to allow the life office to sell its long-term savings and investment products through the bank's 309 branches.
The move aims to give A&L the flexibility to tie up with other providers if changes to the polarisation regime allow multi-tie arrangements in the future.
The deal takes effect this summer subject to contract and regulatory approval. It will give A&L members access to the full range of L&G's Isas, Peps and unit trusts.
It will also see the management of existing A&L unit trusts, Peps and unit trust-based Isa business transfer to L&G as soon as practical once the deal comes into operation. A&L has around £650m in funds under management in 120,000 plans.
A&L says the change will result in modest cost savings compared with the bank's current, largely outsourced, management of these products.
The third part of the deal will see A&L become a marketing associate of L&G subject to regulatory changes.
A&L executive chairman John Windeler says: “Legal & General is a desirable brand in the market and one in which our customers have confidence. This arrangement will enable our salesforce to offer a broader range of competitive products to our customers.”