Lump sum payment for 3 months and got taxed for 20% instead of14%

[Greta123]

I am a student and my department paid me for 3 months as a lump sum instead of each month that I usually get it . To my understanding, I got deducted on a 20% rate instead of the 12-14% that I would have for monthly payments. 

In which form can I check for the refund? How do I know that turbotax knows?

[VictoriaD75]

If you are referring to the amount of withholding that was taken out of your payment, the point of completing a tax return is to reconcile the amount of withholding you actually had with the amount of IRS calculated tax liability. If more was withheld than tax due, you will receive a refund of the difference. 

Complete your return with the information as presented on your tax documents. If too much was withheld, it will present itself as a refund on your tax return. It is part of the calculation on your return. No additional reporting is necessary.