Extract distinct data from one table (Source) into an new table

Flona 

You can use Table.Max function in Power Query as follows

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("rdJBC4MgFAfwryKdPeQz27qPYINOBTtEB7eEdmngEta3X3nIqekuuwiPpz/fX2zb5HwiCV5X1Ij3hNaiUeLV8xmjCx8VlzMiGEFKiqVVyofulOImrVaHPQr+R9GlqNVoSZB6VMXlfXAc0A58pRuUdGYyUvCSEOblY95Um8Usi2qLGusq+tHRYMP8qWlcq/mkpHWABVPmcap62tsPZio3/jEswX7EIhKR2K+faS7T3H5EyH/9ie4D", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [ID = _t, Description = _t, #"Start date" = _t, #"End Date" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"ID", type text}, {"Description", type text}, {"Start date", type date}, {"End Date", type date}}),
    #"Grouped Rows" = Table.Group(#"Changed Type", {"ID"}, {{"All", each Table.Max(_,"Start date"), type record}}),
    #"Expanded All" = Table.ExpandRecordColumn(#"Grouped Rows", "All", {"ID", "Description", "Start date", "End Date"}, {"ID.1", "Description", "Start date", "End Date"})
in
    #"Expanded All"

Hi Flona 

If you want it in DAX you can create a new calculated table as follows:

NewTable =
FILTER (
    Table1,
    Table1[ID]
        = CALCULATE ( MAX ( Table1[Start date] ), ALLEXCEPT ( Table1, Table1[ID] ) )
)

Flona 

You're quite right. There was an error in the code. Try this slightly modified version:

NewTable = 
FILTER (
    Table1;
    Table1[Start date]
        = CALCULATE ( MAX ( Table1[Start date] ); ALLEXCEPT ( Table1; Table1[ID] ) )
)