That money should cover the "future costs of PPI redress, arrears charges and the processing of certain mortgage interest 'first payments'".
Banks have so far set aside £16bn to deal with PPI misselling, which has become the most expensive consumer scandal in British history.
This change has been made while the mutual-owned bank prepares for the announcement of its recapitalisation plan. Preparations for which have included "significant due diligence as well as continued management actions, including a review of conduct related issues", reflecting recent decisions by the financial conduct authority (FCA).
The prudential regulation authority (PRA) has confirmed to the Co-op bank that the previously announced additional Common Equity Tier 1 requirement of £1.5bn by the end of 2014 remains unchanged.
As stated in the unaudited first half accounts, assuming £1.0 billion of Common Equity Tier 1 is raised before the end of 2013, the Bank continues to expect the 2013 year-end Common Equity Tier 1 (Basel III) ratio to be below 9% but above the 7% regulatory minimum requirements.