@ErnieS0 --
The taxpayer is a California resident working remotely for an Illinois Employer.
@shangt --
If your services are entirely performed outside the state of Illinois, your employer is not required to withhold Illinois taxes.
https://www.ilga.gov/legislation/ilcs/fulltext.asp?DocName=003500050K304
If your employer does withhold IL taxes anyway, then you must file a non-resident IL tax return, on which you allocate zero income to IL, in order to obtain a refund.
If your employer does not withhold CA taxes, you must make quarterly estimated tax payments to CA. Your income is 100% taxable by your home state of CA, regardless of its source.
https://www.ftb.ca.gov/pay/estimated-tax-payments.html
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
