If you worked remotely from Florida, your income is considered earned in Florida, You do not need to file a NJ state tax return.
Yes, it is taxable in NJ. See these:
http://www.koscpa.com/newsletter-article/state-tax-consequences-telecommuting/
http://www.journalofaccountancy.com/issues/2009/jun/20091371.html
Anyone have further guidance on this question? I work remotely in Florida but my company considers me an employee based out of NJ and will require returning to its NJ office in the future.
per NJ:
If a nonresident employee works inside and outside New Jersey, only the compensation paid for work performed in New Jersey is subject to New Jersey withholding.
NJ-WT (state.nj.us) at. p. 6
The temporary relief period with regard to employer withholding tax for teleworking employees will end on October 1, 2021. As of that date, employers should cease sourcing income in accordance with the employer’s jurisdiction.