if employer withheld wrong amount of payroll deductions how long do they have to refund it to me?

I noticed on my check that my employer witheld more taxes then they were supposed to. I then went back and checked all of my paychecks and they did this on all of them. I approached my payroll and they stated this would be refunded to me when I file my taxes next year. Is that true? Do I have to wait that long for their mistake?