Dear Kainer,
TDS for providing consulting services is covered under Section 194J of IT Act, 1961. If the amount paid exceeds Rs 30,000/- for individual professional and Rs 10,000/- for the company then TDS @ 10% is deducted.
Few companies, deduct TDS even if the amount paid is far lower for individual professional say Rs 5,000/- They do it because they don't have to remember whether amount exceeded Rs 30,000/- or not. However, it increases their monthly work of inclusion of this amount in their monthly return.
Thanks,
Dinesh Divekar