Comprehensive documentation is absolutely critical for substantiating an offshore profit claim and effectively addressing any inquiries from the Inland Revenue Department (IRD). Key documents include a complete set of sales contracts and purchase orders that clearly show the parties involved and the location of the transactions. Detailed invoices for goods or services, along with corresponding bank statements that reflect the flow of funds originating and terminating outside Hong Kong, are also essential. For trading activities, shipping documents such as bills of lading, airway bills, and customs declarations are vital to demonstrate that goods did not pass through Hong Kong. Additionally, companies should prepare detailed operational charts and organizational structures illustrating where key business activities, such as negotiation, contract signing, and order fulfillment, were performed. Evidence of staff presence, assets, and actual operations overseas is paramount, which can be demonstrated through employment contracts for overseas staff, rental agreements for foreign offices or warehouses, and utility bills. Travel logs and communication records, including comprehensive emails, meeting minutes, and call records with overseas clients or suppliers, are crucial to illustrate the non-Hong Kong based nature of business decisions and execution. A thorough functional analysis outlining the specific activities performed outside Hong Kong, identifying where key decisions were made and executed, and by whom, is also highly recommended to clearly articulate the offshore nature of the profits.