Salary in Contract not the same as stated in the payslip

Hi everyone! Glad to discover this site today.

Call me Sam. I'm 21 yrs old, been working for a month now as a Research Assistant in a BPO company and at the same time a law student (just in my 1st sem ) I'm hesitant to ask the management about this so I'd like to ask for a legal advice regarding my salary; here are the following facts:

1. I signed a contract that my monthly compensation will be amounting to 10,000php + 2,000php meal & transportation allowance
2. I'm still on a probationary status
3. I work from 9PM to 6 AM, Monday to Friday
4. My payslip says that my basic pay is only 8,000php with mandatory deductions and tax

Issue:
1. Did the management overlooked what is stated the contract?;
2. Or is my base pay just 8k because I'm still on a probationary status?;
3. are my night differential and allowances taxable? (Can someone help me how to compute night diff, if it really coincides with their computation?);
4. And is my allowance taxable provided that it does not exceed 25% of my monthly salary?

What should be the proper actions to be done?

Would love to hear from y'all. Thank you.

Sam

1. You should ask them to clarify.
2. Unless specifically stated, then no.
3. Yes.
4. Income (including allowances) should be taxable unless specified.