What do you do if you didn't make enough money to be required to file?

According to this site, if you made less than $12000 in 2018 (and are a certain age and status) then you aren't required to file a tax return.

.... So, what actions should I take if this is the case?

posted

If you are not required to file a federal tax return, then do not file the return.

See iRS Publication 501 page 2 and if you are being claimed as dependent see page 4 for federal tax return filing requirements - https://www.irs.gov/pub/irs-pdf/p501.pdf

However, if you have income from self-employment and the net profit is $400 or greater then you are required to file a federal tax return.

If your state has a personal income tax the requirements for filing are different then federal. You may well have to file a state tax return. Check with your state Department of Revenue or Taxation website for requirements.