Income Tax — Presumptive (44ADA / 44AB Applicability), Advance Tax, TDS

Understand income tax for a software/consulting OPC: when 44ADA presumptive scheme applies, when audit (44AB) is triggered, how advance tax quarters work, TDS deduction and reporting, the difference between OPC tax structure and proprietorship/individual tax structure, and what changes when you draw salary vs dividend from the OPC. Income tax is a state machine with explicit transitions on a fixed clock. Advance tax has four required state transitions per year — miss one and you accrue interest under 234C. 44ADA vs OPC vs salary vs dividend is a configuration choice with downstream cost implications, the same way choosing PostgreSQL vs MySQL has downstream implications. Pick once, model the consequences, revisit only if conditions change (income scale, deductible expenses, capital reinvestment plans). The salary-vs-dividend decision is a particularly engineering-shaped decision: it has a clean mathematical structure (effective tax rate as a function of slab, corporate rate, draw level), it has feedback loops (retained earnings compound at corporate rate, drawn earnings get spent or invested at personal rate), and it has a clear optimum given assumptions. Build the model. Don't guess.