@Apples521 

What was the exact journal entry (JE) made on 12-31-23?  A debit to ??? and a credit to the bank account?

I wouldn't suggest posting this to RE.  That would increase a prior year's net income without ever reporting it as income - your tax preparer will wonder how RE increased.  The answer for the proper entry, IMO, is a debit to A/R and a credit to the debit entry on the 12-31-23 JE, depending on what that is.  If you can provide the 12-31-23 JE, that would be helpful.      

I'm not sure on the exact entry as there isn't a specific entry addressing these specific payments.  I'm seeing a dozen or so YE adjustments for 2023.  Most are for payroll, owners draws, reclassifying undeposited funds to sales or addressing specific BS items which wouldn't apply here.  

The one entry I see "to clear out prior year deposits originally recorded to a liabilty acct" 

Dr Retained Earnings

    Cr Checking

From the dozen entries I see, this is really the only one that looks like it could have been one to balance those wrong payments.

Ahh, if I create an invoice with service item mapped to RE, I can then apply the final payment received in 2025 to that new invoice and the remaining balance of the original?

Say wrong checks total $7,000 and my open balance on the original invoice is $8,000 for a total still owed of $15,000.  They paid me $15k in 2025.  I can create a new invoice "B" mapped to RE for $7,000, and then apply the $15k payment to the $8,000 invoice "A" and the $7,000 invoice "B"?

@Apples521 

"I can create a new invoice "B" mapped to RE for $7,000, and then apply the $15k payment to the $8,000 invoice "A" and the $7,000 invoice "B"?"

You got it!

Thank you!