My wife and I file jointly. My son, who is 19 and lives with us, had a summer job where he earned $4200. Do I file his taxes first?

[NCperson]

it doesn't matter whose return is completed first.

is your son in school full time?  if yes, he is PROBABLY your dependent. his income level doesn't matter. 

if he is not in school and his incomes exceeds $4200, he can not be your dependent.  that $4200 line is important. 

just follow the prompts in TT to determine whether he is a dependent. 

[tkstock]

He is in high school full-time, yes.  He is a dependent.

But I do need to file taxes for him separately?

Thanks for your response!

[NCperson]

@tkstock - 

the filing requirement for your student is he must file his own tax return  if any of these are true

a) he received a 1099-misc form for his work

b) he had federal or state taxes withheld (the only way to get the money back is by filing)

c) he made more than $12,200

if they are all false, there is no need for him to file.  DO NOT put his income on YOUR tax return! 

if he files, be sure he clicks the button on HIS tax return that he can be claimed by someone else,

[SteamTrain]

IF one is required, it would be done as a separate tax file.  IF you use the Online software, make sure you use an entirely different account from yours...any attempt to use your own account would destroy one of the tax files, depending on whose was done first,

1)  IF he gets a W-2 for that work, and Federal or state taxes were withheld, then a tax return "can" be filed for him  to get any withholding taxes back.  SS and Medicare taxes are not refunded.  But do it together with him...he needs to see how it is done.   If no Federal or state income taxes were withheld, then his income is low enough that a federal tax return would not be required, but make sure you add in any bank interest to his income too.   States vary though.  I don't think any would require a tax return at that income level, but I'm not sure, ..check your state's online tax page to see what the minimum income would be.

2)  if the work done was for cash, or a 1099-MISC is issued for his work, then a tax return would be required to be filed for him.  He would have to pay Medicare and SS taxes on the gains from that "cash" work.  It is considered Self-Employment income.

3)  I recommend preparing and filing your own taxes first.  That prevents any problems with your own filing should you accidentally set his dependency status wrong on his tax file.

4) For #1 above, his tax return should be able to use the Online "Free" version...unless he also has a brokerage account that has stock bond sales for 2019.   For #2 above, his tax return would require the use of the Online SE version, which is not free.   

(Many of us usually recommend the use of the Desktop/download versions of TTX for people who have multiple tax returns to file.  Mostly because you can work on multiple files, and create test files too, and would cover both situations above.   Deluxe or higher should be used, but be careful when buying any Deluxe, since there are some versions that don't include a free state download (If bought direct from TTX, it always includes one state software set).  Even if the state download is included, the E-filing for the state is an added $25 (except NY)...but the state forms could be mail-filed for the cost of your paper and postage)