Entry into force timing for tax treaty: staggered effective dates for withholding and income taxes across states. The Agreement requires mutual written notification through diplomatic channels before it enters into force on the date of the later notification. It prescribes staggered, state-specific effective dates: in India the treaty governs withholding taxes for amounts paid or credited on or after the first April of the calendar year following entry into force and applies to taxes on income for fiscal years beginning on or after that April; in Iceland withholding taxes apply to income derived on or after the first January of the calendar year following the later notification and other income taxes for tax years beginning on or after that January.