Question regarding how to distinguish supplemental income from normal W-2 wages wile filing tax return

[sunny13]

Hi,

Last year (2020), I got a supplemental income of $2000 by working on 2 holidays (Dec 24th and 25th). But that income is included in the Box 1 of my W-2 form. How can I report is separately so that I have to pay less tax on this supplemental income than my current bracket. As the supplemental income is taxed at a flat rate of 22 % which is less than my current tax bracket. 

[Mike9241]

you misunderstand about supplemental income. you pay taxes on it at whatever tax brackets it falls into. it's the employer that can withhold at a flat 22% rate. report the w-2 as is. 

[sunny13]

Mike,
1) 
My employer withheld taxes on the supplemental income at a higher rate than my current bracket. Does it mean that they used the what is called "The aggregate method"?

2) 
In case if they had withheld the taxes at 22 % and my tax bracket was higher, then did I need to pay the rest of the taxes while filing the tax returns ?