How the calculation works on PKR 4,00,000 / month
400,000 a month is a salary only a small slice of earners reach, and it puts you in the top 35% bracket, the highest the salaried table goes. That's 4,800,000 a year. After the 616,000 fixed amount plus 35% on the income above 4,100,000, your tax comes to 861,000 a year, or roughly 71,750 a month. Your effective rate is 17.94%, with a marginal rate of 35%.
That works out to roughly Rs 71,750 a month deducted from your gross, leaving you with Rs 3,28,250 take-home. Your effective tax rate is 17.94%, even though your marginal rate is 35%.
What changes if you're not salaried?
Both ordinary regimes are heavy here, but the non-salaried table tops out even higher than the salaried 35%. The one route that goes the other way is registered IT export income at a flat 0.25% on foreign-currency receipts. On 4,800,000 a year, the gap between that and being taxed as a salaried earner runs into many lakhs.