State tax filing

They are saying he has to pay tax on severance based on it being earned over a 17 year career.  This is the answer from kpmg but I don’t agree with them.  So I am

asking if anyone else has better advice.  
They say tax each year from 2004 forward.

 

 

  But a friend in tax mentioned to me NY safe harbour rule which says NY should only the last 3 active years of severance pay, so 2018 forward.  Which would mean he was not physically present in NYS those years and not owe taxes on the payout.  That’s $8,000 reasons why I want to know if anyone else had dealt with this situation. I’d be a fool to just trust kpmg alone.  They have made errors in the past