I am working in QuickBooks Desktop and I am still struggling with this issue. The previous explanations are too vague. Here are the specifics for this one large vendor, lets call them ABC Co., who issues over a 1000 invoices to us each year. It is a very large account and challenging to keep track of all the details.

2018 - $24,904.01 on 4 ABC Co. vendor invoices showing open in QB but considered paid by ABC Co.

*2018 corporate taxes have been filed, 2018 is closed out

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2019 - $3081.49 in vendor invoices showing open in QB but considered paid by the vendors

$5937.54 in open credit memos as well for this same vendor

*2019 corporate taxes have been filed, 2019 closed out

I'm thinking I could apply the 2019 open credit memos to the 2019 open invoices and at least clear out those invoices, but that will still leave me with $2856.05 in invoices to clear out for 2019 for this vendor and I still don't understand how to handle the invoices from 2018 that are still open. 

My biggest concern is that I do not want my actions to impact previous tax returns that have already been filed.

Thank you for your continued support and patience with my questions!