18000/00

If the security guard is working as an employee with you then his total salary for the year will be 18000×12= 216000, which is less than the exemption limit , hence no tds.

but if you are paying this amount to any security agency which in turn pays it to the security guard then tds will be 10% of 18000 which should be deducted every month.

Whether the security guard engaged as an employee or on contract basis ? If employer, TDS on slab rate basis under section 192 to be deducted. On the other hand if the security guard is engaged in terms of contractual obligation then TDS to be made as per the provisions of section 194 C either at 2% in case of Companies or at 1% in case of individuals and firms, where the amount exceeds Rs. 30,000 for single payment or exceeds Rs. 75,000 in aggregate for the whole year.