Add an option to the Deposit Products definitions, so that whenever some of the interest rate terms are changed (interest rate, calculation basis or payment frequency), the user can opt to apply the new terms either:
(a) only to NEW deposit accounts opened in that product from that point onwards; OR
(b) to ALL accounts currently opened in that product.
Some changes in savings accounts conditions, especially concerning interest calculations, often need to apply to ALL accounts. For example: it is common that organizations change their interest rate policies to match the market trends and for those savings products that are by definition flexible (current/ savings accounts) these changes need to apply to all the active deposit accounts. For other types of products, such as fixed deposits, the rate should remain fixed once the account is activated and the interest rate policy changes apply only to NEW deposits opened after the rate changed.