New York has a rule called the "convenience of the employer rule". This means that if your husband's job is based in New York but works outside of New York for his own convenience (rather than because his employer requires him to work in Florida), then New York can tax all of his income - not just the days he physically worked in New York.
This means that even if he only physically works in New York 8 days a month, New York may still consider 100% of his income as New York sourced income if:
1. His official work location is in New York
2. He's working outside of New York by his choice rather than by necessity for the employer.
If the convenience of the employer rule applies, you may not be eligible for a refund of all those NY taxes. All of the income that he earned for that employer would be taxable to NY. The only ways around this would be if:
- his employer specifically assigned him to work outside of New York (employer necessity)
- he has a formal work arrangement stating that Florida is his primary work location
