I was hired and provided me the job offer over the phone they told me the exact annual income when we singed the contract we thought since it is annual it is only for a year which is equivalent for 12 months that is what we expected but when we got our payslip we ask our HR for we think the amount that we are getting every cutoff or every month is not enough for the said annual income. HR told us that the annual amount that was discussed to us is 13 month inclusive. they included the 13th month pay to the annual salary amount that we are going to get. is that legal? can 13th month pay be included in the annual amount that was offered unto us? please help need legal advise on this