How the calculation works on PKR 7,50,000 / month
750,000 a month is rare air, founder or top-executive territory, and your effective rate is closing in on 26%. That's 9,000,000 a year. After the 616,000 fixed amount and 35% on the income above 4,100,000, your tax is 2,331,000 a year, or about 194,250 a month. The detail I'd flag here: at 9,000,000 you're sitting just under the 10,000,000 line where the 9% surcharge starts, so you have a little room left.
That works out to roughly Rs 1,94,250 a month deducted from your gross, leaving you with Rs 5,55,750 take-home. Your effective tax rate is 25.90%, even though your marginal rate is 35%.
What changes if you're not salaried?
On 9,000,000 a year, ordinary non-salaried rates run above the salaried 35%, and registered IT export income at a flat 0.25% is still by far the biggest structural lever. At this level the difference between being taxed as salaried versus on export income is measured in tens of lakhs a year.