Create a script concatenation Property - M-Files Cloud Vault

Compliance Kit's Utilities module has a sequences functionality that can use value list properties to determine when a new sequence is needed. If you can get the month and year into two value list properties somehow then you can use this module to get the monthly sequences.

In this example Sequence value property is automatically set by the Utilities module with a running number for each month and Quote number is an automatic text property concatenating the month, the year and the sequence value.

Sequence configuration in Utilities module:

Quote number concatenation:

I hope this gives you an idea of how to set it up.