Aging

Without sample data Andrewutter12 this is hard to do as I don't fully understand your scenario. However, I mocked something up. I turn this:

Into this:

So my sample data has some invoices fully paid, partially paid, and not at all paid. I also assumed the due date was 30 days after the sales date. This is the M code to do it.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WCvZS0lEyNDO2MADS5vrGhvpGBkYgtomBgYFSrE60kjOyCkugNEyFLlwJxBALIADSFvpwM4B6kM2AK0DYomtshmKGJRCArUG4wwikIBYA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Journal = _t, #"Invoice Number" = _t, #"Transaction Date" = _t, Amount = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Transaction Date", type date}, {"Amount", Currency.Type}}),
    #"Grouped Rows" = Table.Group(#"Changed Type", {"Invoice Number"}, {{"Balance", each List.Sum([Amount]), type nullable number}, {"AllRows", each _, type table [Journal=nullable text, Invoice Number=nullable text, Transaction Date=nullable date, Amount=nullable number]}}),
    #"Added Date Due" = Table.AddColumn(#"Grouped Rows", "Date Due", each Date.AddDays(Table.SelectRows([AllRows], each [Journal] = "SJ")[Transaction Date]{0}, 30), type date),
    #"Added Days Past Due" = Table.AddColumn(#"Added Date Due", "Days Past Due", each Duration.Days(DateTime.Date(DateTime.LocalNow()) - [Date Due]), Int64.Type),
    #"Added Bucket" = Table.AddColumn(#"Added Days Past Due", "Bucket", each if [Days Past Due] < 31 then "Current"
else if [Days Past Due] < 61 then "31-60"
else if [Days Past Due] < 91 then "61-90" 
else "90+ days", type text),
    #"Filtered Rows" = Table.SelectRows(#"Added Bucket", each ([Balance] <> 0)),
    #"Expanded AllRows" = Table.ExpandTableColumn(#"Filtered Rows", "AllRows", {"Journal"}, {"Journal"})
in
    #"Expanded AllRows"

How to use M code provided in a blank query:
1) In Power Query, select New Source, then Blank Query
2) On the Home ribbon, select "Advanced Editor" button
3) Remove everything you see, then paste the M code I've given you in that box.
4) Press Done
5) See this article if you need help using this M code in your model.

If you need more help Andrewutter12 please give us some sample data and expected output that we can use. Screenshots are fine for expected output, but not for sample data.

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