Method of verification for TAX Returns/Paid Amount

[CH]

Dear All,
It would be appreciable if some one could guide me about the method of verification used by HSMP staff to verify tax returns in Pakistan.

Dothey verify NTN on website only? OR

do they send verification request in written to tax department?

In case of two jobs at a time. If individual salaries are less than taxation limit but in combined form exceeds taxation limit. Each company does not deduct tax in this case. Now if we claim points under earning, with no records of earning in taxation office, what are the chances of getting sucess.

Best Regards,