Income tax calculation is wrong

[clarkej]

Clues like this may shed light

Income tax calculation seems to be incorrect

ERPNext calculates income tax deduction based on the projected annual salary payable to the employee which is why the income tax deduction per month varies. And, in the last month of the payroll period the system calculates the income tax deductible for the whole year and then adjusts last months deduction to the balance amount.

Some test case trial and error learning with say a spreadsheet will work too?