Tax on more than 50L Income

Can someone explain to me how exactly does the tax work once ur yearly income exceeds 50L? As I understand, currently there is a surcharge on tax, but there is also surcharge relief as well? I read some articles online and was surprised to learn that surcharge is applied on the total tax you pay, not on the extra earnings above 50L (unlike tax slabs). I have some (probably dumb) questions on the topic, hope someone can help. 1. Is amount of 50L on total income or on total taxable income (after various deductions) 2. If I understand the marginal relief correctly, if two people have income as 50L and 51L, both of them will essentially have same post tax income because you will be paying the complete extra 1L as tax? 3. Are there other things I should be aware of regarding this? I appreciate any help you can provide, thank you!