When gifting immovable property in India, stamp duty is payable based on the property's value. The Sub-Registrar's office, where the property is located, determines this valuation. They typically use the government-fixed 'guideline value' or 'circle rate' for the area. While this guideline value aims to reflect market value, it can sometimes be lower or higher than the actual market price. You can obtain an official valuation slip from the Sub-Registrar for a small fee.