Maxifs - Power Query

Ok Anonymous - it isn't a function per se, but a series of functions using Table.Group and Table.Max. The code is below. It turns this:

into this:

It does it by grouping by the contract and determing the max Evaluation Date, then comparing it to each date for a given contract, returning true or false. These are real true/false values (like Excel's TRUE() and FALSE()). 

I used my own data because you posted data in an image, which is great for expected results, but I cannot copy and paste it in. The links I provided earlier show you how to supply data to the forum in a usable format.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WqlDSUTLUN9Q3MjAyQGbG6mCRM0bIVQIFjBByRjjkLIFME7iZsQA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Contract = _t, #"Visit Date" = _t, #"Evaluation Date" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Visit Date", type date}, {"Evaluation Date", type date}}),
    #"Grouped Rows" = 
        Table.Group(
            #"Changed Type", 
            {"Contract"}, 
            {
                {
                    "AllRows", 
                    each 
                        let
                            varTable = _
                        in
                    Table.AddColumn(
                        _, 
                        "Max Date", 
                        each 
                            let
                                varDate = [Evaluation Date]
                            in
                            Table.Max(varTable, "Evaluation Date")[Evaluation Date] = varDate
                        ), type table [Contract=nullable text, Visit Date=nullable date, Evaluation Date=nullable date, Max Date = nullable date]}
            }
        ),
    #"Expanded AllRows" = Table.ExpandTableColumn(#"Grouped Rows", "AllRows", {"Visit Date", "Evaluation Date", "Max Date"}, {"Visit Date", "Evaluation Date", "Max Date"})
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.