You can't other than to ask the person you suspect.
If someone else claimed you,
as a dependent, inappropriately, and if
they file first, your return will be rejected if e-filed. You would then need
to file a return on paper, claiming yourself, if appropriate. The IRS will process
your return and send you your refund, in the normal time. Shortly (up to a
year) thereafter, you’ll receive a letter from the IRS, stating that your
exemption was claimed on another return. It will tell you that if you made a
mistake to file an amended return and if you didn't make a mistake to do
nothing. The other party will get the same letter you did. If one of you doesn't
file an amended return, unclaiming the exemption, the next letter, from the
IRS, will require you to provide proof. Be sure to reply in a timely manner.
Winner gets the tax benefits; loser gets to pay the IRS back with penalties
and interest.
The usual suspects are:
- The parent the child lives with.
- The other parent. .
- Some other member of the household (e.g. grandparent)
- Someone else the child lived with for part of the year
With the new tax law (2018), it doesn't matter as much, as previous years, whether you can claim yourself, if you are under 24 and have primarily earned income
