“Monies” and “moneys” are both the plural form of money in English. Their usage, however, is not exactly the same. “Monies” and “moneys” are interchangeable most the time, but not all the time.
Traditional English grammar books say that “money” is uncountable, therefore it does not have a plural form. However, as most linguists agree, languages are not static but are lively and ever-evolving.
“After my trip to Asia, I have three different kinds of moneys in my wallet.”
This sense of “moneys” means “currencies”.
“I have my own business. Three clients owe me sums of $100, $200 and $300. My bookkeeper records the three entries in the “monies due” column in my accounting books. The moneys due to my business are $600.”
In general, the usage of “moneys” is more general and casual. “Monies” is used more in an academic sense, as in traditional economics textbooks (modern economics textbooks may start using moneys). So, it seems to be more orthodox, or even authoritative in that sense to use “monies”.
Nowadays, “monies” is usually used more by professionals that require taking economics courses in their training, such as bankers, accountants, MBAs, etc.
In daily use, we use “moneys” more often than “monies”, probably because less people know (or care to know) the “proper” plural form of money is “monies”.
This site is an extension of TwoKindsOfMonies.blogspot.com in case you spell the plural of money as moneys, not monies.
For all articles, please go to TwoKindsOfMonies.blogspot.com.