After-tax income = pre-tax income-{(pre-tax income-expenses deducted) * tax rate-quick deduction}

Income before tax = (income after tax-expenses deducted * tax rate-quick deduction) /( 1- tax rate)

Pre-tax income = (4800-1600 *15%-125)/(15%) = 5217.65 yuan.

Attached calculation basis:

Personal income tax payable = (taxable income-deduction standard) * applicable tax rate-quick deduction

The deduction standard is 1600 yuan/month.

If it does not exceed 500 yuan, the tax rate is 5%, and the quick deduction is 0;

For the part exceeding 500 yuan to 2,000 yuan, the tax rate is 10%, and 25 is deducted for quick calculation.

For the part exceeding 2,000 yuan to 5,000 yuan, the tax rate is 15%, and the quick deduction is 125.

For the part exceeding 5,000 yuan to 20,000 yuan, the tax rate is 20%, and the quick deduction is 375.

For the part exceeding 20,000 yuan to 40,000 yuan, the tax rate is 25%, and the quick deduction is 1.375.

For the part exceeding 40,000 yuan to 60,000 yuan, the tax rate is 30%, and the quick deduction is 3375.

For the part exceeding 60,000 yuan to 80,000 yuan, the tax rate is 35%, and the quick deduction is 6375.

For the part exceeding 80,000 yuan to 100000 yuan, the tax rate is 40%, and the quick deduction is 10375.

For the part exceeding 100000 yuan, the tax rate is 45%, and the quick deduction is 15375.