@kgerman007 --
Yes. If you never filed a 2020 DE non-resident tax return, you should do so now. All the income you earned by working in DE is taxable by DE. Note that you must use a 2020 desktop version of TurboTax to file a 2020 return. If necessary, you can purchase that here:
https://turbotax.intuit.com/personal-taxes/past-years-products/2020/
You cannot file a 2020 return online. You must print and mail it.
Once your 2020 DE return has been processed, you can then amend your 2020 NJ return to correct the withholdings and to claim the "other state credit" for the taxes paid to DE. Note that in order to claim a refund, the amended return must be filed within three years from the original due date of the return or two years from the time the tax was paid, whichever is later. An amended return must be paper-filed.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
