A couple of issues:

1. salary changes over time. At every least you'd have a to/from, and the relationship would be employee (1-->N) salary .

2. you'd probably want a separate payrollPeriod table which establishes the frequency. PayrollPeriodID + To/From at least. You might also have different items on different frequencies so you might want to account for that.

Assuming your Payroll table represents each payroll transaction, it might look something like:

PayrollID

EmployeeID

PayrollPeriodID

SalaryID --<-- not strictly necessary since you could derive it from the other 2 FK's. Still commonly added in.

Your income and deductions would then be associated to the payrollID they're being paid in. I would usually have a separate table to do the correlation, since the assumption would be that you might have multiple deductions or income in a given period.

So the income would be looped in perhaps as such:

AdditionalIncomePaid table

IncomeID

PayrollID

--additional columns as needed

And the deductions would be associated in the same fashion.