SLA Rule for Credit Memos based on Accounting date of Invoice being Credited

Summary:

Looking to override Receivables accounting on a CM relating to an Inv accounted in a prior Financial Year

Content (required):

We have a requirement to override the Receivables accounting of a Credit Memo when the invoice being credited was accounted in a prior Financial Year. I have had a look at using Account Rules or a User-defined formula but I could not find any sources which could check the accounting date of the credited invoice against the start date of the current reporting year. Has anyone come across a similar requirement, and if so how did you achieve this?