Taxable amount = (taxable income-deduction of expenses) * tax rate-quick deduction.

Taxable income = (after deducting expenses * tax rate+quick deduction+taxable amount)/tax rate = (1600 *15%+125+345)/15% = 4733.33 yuan.

The provident fund and social security fund paid according to regulations do not need to pay taxes, so your actual income is higher than 4733.33 yuan.