Straight-Line Method (SLM) allocates the depreciable amount equally over each year of the asset's useful life. Formula: Annual Depreciation = (Cost - Residual Value) / Useful Life. This method is simple and widely used because depreciation amount is constant each year. Book value decreases uniformly. The method is appropriate for assets that provide consistent benefits over their useful life. Accumulated depreciation table shows opening balance, depreciation for current year, and closing balance. SLM is suitable for buildings, furniture, fixtures, and similar assets. The method assumes that benefit derived from asset is uniform each period. Partial period depreciation is calculated as: (Cost - Residual Value) × (Months/12) / Useful Life. When asset is acquired mid-year, depreciation is calculated from month of acquisition. When asset is disposed, depreciation is calculated till month of disposal. Disposal results in either gain or loss on sale (difference between sale price and book value). SLM provides easy and transparent reporting; users understand depreciation easily. The method is most commonly used for tax and financial reporting in India. Under Income Tax Act, SLM is default method unless specified otherwise. Exam tip: Master the SLM formula and its application to full-year, partial-year, and disposals; practice creating depreciation schedules; understand gain/loss calculation on disposal.