As I said before, IRS Notice 2014-7 does NOT exempt a person from FICA. It only applies to income tax. You are welcome to look at the actual Notice 2014-7 and the IRS FAQs (particularly #12) to confirm that.
There ARE some reasons that a person may not be subject to FICA, such as if the person you are taking care of is considered your employer and that person is your child. But that has to do the Household Employee laws, not anything to do with Notice 2014-7. If the person is your child, it is quite possible that Washington and Oregon are treating it differently, which is perfectly legal. It is very common (even within the same state) for some programs to treat you as an employee of of the disabled person (which would make you a Household Employee), and other programs treat you as an employee under a third-party (which falls under different rules, making you subject to FICA even if the disabled person is your child).
https://www.irs.gov/pub/irs-drop/n-14-07.pdf
https://www.irs.gov/individuals/certain-medicaid-waiver-payments-may-be-excludable-from-income
