Power Query Transform columns related to processes and dates of those process

You'd have to replace my "Source" row with your excel source. You might have some transformations needed prior to my code, but this should do what you want:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45W8gxzVNJRMjUwMABShvqG+kYGRiZAphFMxAgmYggTMYaIxMYCAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [TAX_TYPE = _t, PROCESS_1 = _t, DATE_P1 = _t, PROCESS_2 = _t, DATE_P2 = _t, PROCESS_3 = _t, DATE_P3 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"TAX_TYPE", type text}, {"PROCESS_1", Int64.Type}, {"DATE_P1", type date}, {"PROCESS_2", Int64.Type}, {"DATE_P2", type date}, {"PROCESS_3", Int64.Type}, {"DATE_P3", type date}}),
    #"Unpivoted Columns" = Table.UnpivotOtherColumns(#"Changed Type", {"TAX_TYPE"}, "Attribute", "Value"),
    #"Split Column by Delimiter" = Table.SplitColumn(#"Unpivoted Columns", "Attribute", Splitter.SplitTextByEachDelimiter({"_"}, QuoteStyle.Csv, true), {"Attribute", "ID"}),
    #"Remove P from ID" = Table.ReplaceValue(#"Split Column by Delimiter","P","",Replacer.ReplaceText,{"ID"}),
    #"Replaced PROCESS" = Table.ReplaceValue(#"Remove P from ID","PROCESS","VALUE",Replacer.ReplaceText,{"Attribute"}),
    #"Replaced DATE" = Table.ReplaceValue(#"Replaced PROCESS","DATE","DATE_PROCESS",Replacer.ReplaceText,{"Attribute"}),
    #"Added PROCESS" = Table.AddColumn(#"Replaced DATE", "PROCESS", each "PROCESS_" & [ID], type text),
    #"Removed ID" = Table.RemoveColumns(#"Added PROCESS",{"ID"}),
    #"Pivoted Column" = Table.Pivot(#"Removed ID", List.Distinct(#"Removed ID"[Attribute]), "Attribute", "Value", List.Max),
    #"Set Types" = Table.TransformColumnTypes(#"Pivoted Column",{{"DATE_PROCESS", type date}, {"VALUE", Int64.Type}})
in
    #"Set Types"

Hi RicardoContrera, different approach here.

Result

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45W8gxzVNJRMjUwMABShvqG+kYGRiZAphFMxAgmYggTMYaIxMYCAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [TAX_TYPE = _t, PROCESS_1 = _t, DATE_P1 = _t, PROCESS_2 = _t, DATE_P2 = _t, PROCESS_3 = _t, DATE_P3 = _t]),
    Transformed = Table.FromRows(List.TransformMany(Table.ToRows(Source),
        each List.Split(List.Skip(_),2),
        (x,y)=> {x{0}} & y ), type table[TAX_TYPE=text, VALUE=number, DATE_PROCESS=date]),
    Ad_Process = Table.AddIndexColumn(Transformed, "PROCESS", 1, 1, Int64.Type),
    Transformed2 = Table.TransformColumns(Ad_Process, {{"VALUE", Number.From}, {"DATE_PROCESS", Date.From}, {"PROCESS", each "PROCESS_" & Text.From(_), type text}})
in
    Transformed2

Hi RicardoContrera 

Another solution

let
Source = Your_Source,
Date_Column = List.Select(Table.ColumnNames(Source), each Text.StartsWith(_, "DATE")),
Process_Column = List.Select(Table.ColumnNames(Source), each Text.StartsWith(_, "PROCESS")),
Data = Table.AddColumn(Source, "Data", 
     each Table.FromColumns(
            {Process_Column,
             Record.ToList(Record.SelectFields(_, Date_Column)),
             Record.ToList(Record.SelectFields(_, Process_Column))},
            {"PROCESS", "DATE_PROCESS", "VALUE"})),
SelectColumns = Table.SelectColumns(Data,{"TAX_TYPE", "Data"}),
Expand = Table.ExpandTableColumn(SelectColumns, "Data", {"PROCESS", "DATE_PROCESS", "VALUE"}, {"PROCESS", "DATE_PROCESS", "VALUE"})
in
Expand

Stéphane