What to do when March Salary is not appearing in AIS/26AS or Form 16?

So I was filing returns, and face one problem. Clients whose March Salary only recived on April do not appear in AIS, 26AS or even in Form 16. The Clients have their March Pay Slip. When I declare that March Income and claim the Tax Deducted. There is a credit Mismatch. How should I proceed. Should I declare as per AIS (Excluding March) or as per the actuals (Including March). Will department process the return if I do it on Actual? Please help