Westpac will record A$165 million of additional tax expense in its 2011/12 results as a result of amendments to the Taxation of Financial Arrangements legislation.The amendments had an adverse effect on certain liabilities that were consolidated as part of Westpac's merger with St George Bank. The bank said it did not expect any further tax costs to arise from the merger.TOFA legislation was amended this week and will apply retrospectively. The $165 million expense covers additional tax between 2011 and 2014.Westpac's capital ratio will be reduced by about six basis points.