Why TDS short deduction goes unnoticed until a tax notice arrives

TDS short deduction goes unnoticed because the decision about which section applies — and therefore what rate to withhold — gets made once, at the point an invoice or payment is booked, by whoever is processing it that day, and nothing in the normal accounting cycle revisits that classification afterward. If a payment was coded as a contract payment instead of professional fees, or as goods instead of services, the wrong rate gets applied consistently for the whole year, and it looks internally consistent right up until the department's system matches it against the counterparty's return.

Where the misclassification actually originates

• A new vendor type or service that doesn't cleanly fit an existing TDS section code, so someone picks the closest existing one under time pressure.
• A composite invoice covering both goods and services, with TDS applied to the full value under a single section instead of split correctly.
• A payment below the threshold for TDS in isolation, but which should have been aggregated with earlier payments to the same vendor during the year and crossed the threshold in aggregate.
• A rate change mid-year that gets applied to new transactions but never flows into the ERP's default vendor configuration for a vendor set up before the change.
• Reimbursement of expenses booked without TDS on the assumption it's a pure pass-through, when part of it was actually a fee component.

What actually catches it before the notice does

A section-by-section review of vendor categorisation against actual invoice substance — not just the TDS payable account tying to the return filed — is what surfaces a misclassification early. By the time a notice arrives, the exposure includes interest and the short-deduction amount itself, which a mid-year review of classification would have caught for a fraction of the cost.