Principles of preparation of financial statements upon change of currency in accounting.
1. When changing the accounting currency, in the first period after the change, accountants convert the balances of accounting books into the currency of the new accounting at the transfer rate of a commercial bank where enterprises frequently trade at the date of conversion of currency in accounting.
2. The rate applied to comparative information (previous column) in income statements and cash flow statements:
When presenting comparative information in income statements and cash flow statements of the period of conversion of currency in accounting, units apply the average transfer rate of the period preceding the change period (if the average exchange rate is approximate the actual cost).
3. When changing the currency in accounting, enterprises must present clearly in the notes to financial statements reasons of change of the currency in the accounting and impacts (if any) for financial statement due to changes in currency in accounting.

Source: Circular 200, Article 108