From Salaries (section 192). The TDS is based on the tax at the applicable rate on the estimated income of employee for the year. Employer must not deduct TDS on all the non-taxable allowances like conveyance allowance, rent allowance, medical allowance and the deductible investments under sections like 80C, 80CC, 80D, 80DD, 80DDB, 80E, 80GG and 80U. No tax is required to be deducted from source unless the estimated salary exceeds the amount not chargeable to tax. The employer can increase or decrease the amount to be deducted to make the adjustments for any previous deficiency or excess deduction.