TDS, advance tax and filing

Tax is collected during the year itself, not only at assessment: tax deducted at source (TDS) takes tax from payments like salary and interest, tax collected at source (TCS) takes it from specified receipts, and advance tax requires taxpayers to pay their estimated liability in instalments. Worked example: an employer paying a salary deducts tax each month from the salary itself — the employee does not wait until year-end, and the deducted tax is credited against the final liability computed in the return.