MANAGEMENT ACCOUNTING, COSTING, AND BUDGETARY CONTROL

Management accounting enables enterprise decisions before their financial consequences become visible in published accounts. Yet apparently precise cost figures can mislead when classification, capacity assumptions, causal attribution, managerial incentives or uncertainty are poorly specified. This chapter critically develops management accounting, costing and budgetary control as an integrated system of decision support, organizational coordination and accountability. A transparent, purposive synthesis brings marginal economics, cost-behaviour research, agency theory, interpretive accounting theory, contingency perspectives, activity-based management, budgeting scholarship and performance-control theory into dialogue with professional guidance. Twelve approved domains cover cost concepts, conventional and activity-based costing, cost-volume-profit analysis, constrained decisions, customer profitability, operating and cash budgets, standards and variances, multidimensional controls, analytics and ethics. Official Rwandan enterprise evidence situates the argument in a business environment characterized by extensive informality and heterogeneous productive capacity. A fully hypothetical Kigali food manufacturer supports reconciled product-cost, contribution, process-costing, break-even, flexible-budget, variance, customer-profitability and make-or-buy calculations, supplemented by an activity-based costing extension. International comparisons assess the transferability of sophisticated costing systems to resource-constrained enterprises. The principal thesis is that management accounting becomes useful not through ever finer numerical detail, but through fit between a decision, its relevant economic consequences, sufficiently credible information, organizational authority and legitimate stakeholder constraints. The proposed integration is an analytical synthesis, not a newly empirically validated model.