Yes, citizens and GC holders are required to file taxes every year if they make more than certain amount for the year per IRS website. They provide certain thresholds for income required to file taxes based on filing status. I could have posted a screenshot, but I am not sure if I am allowed to, so I’ll just include a link. The way I understand it, if you make below certain limit you are not required to file taxes. Even if my husband reports the income earned while he lived overseas, it is still below that income threshold required to file taxes. I am a bit confused when it comes to this.
https://www.irs.gov/newsroom/who-needs-to-file-a-tax-return