I am helping a friend clean up her QBO company file.  She uses a point of sale system to record all of her sales.  She does not enter invoices in QB.  She records her monthly Accounts Receivable using journal entries each month.  The end of year 2019 balance for her A/R account does not match the A/R report from her POS system.   A $2,000 AR payment was received in 2019 (deposited into bank account), but not applied to A/R. The books have been closed for 2019 and taxes files.  How do I now account for the payment without affecting the income in 2020?  My first thought it to make a prior year adjustment JE and offset it against Retained Earnings.  Would that be ok?