I'm sharing about my MIL's misadventures in my journal but had a specific tax question. She hasn't filed taxes since the mid 90's under the auspices that she is low income enough that she is exempt from filing. Doublechecked the IRS income thresholds and that is indeed correct.
I do note however that she was the primary caregiver for her invalid daughter up until about 2009, and its possible that by not filing, she missed out on some tax credits. So the question is, how many years can I go backwards when filing a tax return on her behalf?