The disclosure statement that is required under IAS 12 (Income Taxes) would typically include information about the calculation and recognition of income taxes, including the impact of taxes on the income statement and balance sheet, as well as the nature and amount of temporary differences and the related deferred tax assets or liabilities. Therefore, among the options provided, the one that aligns with the type of disclosure typically required by IAS 12 is:

B. The current tax expense for the year ended 31 December 20X1 of CU 950 relates to turnover generated during the year.

This statement indicates that the current tax expense for the year can be attributed to a specific source, in this case, the turnover generated during the year, which is relevant information for stakeholders to understand the tax implications of the entity's operations.

Option A, while relevant to the equity method of accounting for income taxes, does not specifically relate to the disclosures usually made under IAS 12, which focuses more on the impact of taxes on profit or loss and other comprehensive income. Option C, on the other hand, is not a disclosure typically required by IAS 12, as it pertains to a change in tax rates, which is not a standard disclosure under the standard.

Hence, the most appropriate choice for a disclosure under IAS 12 would be:

B. The current tax expense for the year ended 31 December 20X1 of CU 950 relates to turnover generated during the year.