What he is asking for is a loan and not an advance, as advance is generally, recovered in one shot (as his salary is 12000, this is not possible).
Now, normally, the loan is given as maximum of 2 salaries, so the recovery can be done easily.
You will need to form a loan form, the employee has to fill the same, sign the same and also ask him to give 2 surety who are working with you and who will pay the loan, if the person absconds.
From India, Mumbai
Ensure that the employee TOTAL DEDUCTION in salary slip does not exceed 50% against the TOTAL GROSS SALARY every month as per rules mentioned in Payment of Wages Act. In that way you have to calculate the monthly EMI for the loan you have given along with other deductions like PF,ESI,PT etc.
From India, Chennai