The two-word expression originary interest does not need to be hyphenated.
However, should the four-word expression individual originary interest rate be hyphenated somewhere?
The two-word expression originary interest does not need to be hyphenated.
However, should the four-word expression individual originary interest rate be hyphenated somewhere?
Short answer - no.
The 'rules' around whether a compound noun should be hyphenated or not are extremely inconsistent, but compound nouns made from an adjective and a noun are not usually hyphenated, eg full moon, red tape, and your example, pure interest.
Occasionally you will find a compound noun that is not normally hyphenated, but which may be written with a hyphen in certain contexts. The usual reason for this is to avoid ambiguity. One example of this might be "bus stop". As it is a compound of two nouns but not joined together, it is inconsistently written - sometimes with a hyphen, sometimes without. But, if you were writing a sentence like "I made the bus stop" there would be an ambiguity - it could sound like you forced the vehicle to come to a stop, or that you reached the place where you wait for a bus. Using a hyphen would help you clarify you meant the latter.
With your example, there is no such ambiguity - it can only be understood one way, so there is no need to add a hyphen to a compound that does not normally have one.