From 306a9628f185fe88f7369be0d31a52a1921990b9 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 10 Oct 2025 20:29:14 +0000
Subject: [PATCH 1/2] Initial plan


From e0f84037f46303f2806754029a2fdc4ec98403f2 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 10 Oct 2025 20:38:33 +0000
Subject: [PATCH 2/2] Fix Number of Months date calculation bug

Co-authored-by: MSBrett <24294904+MSBrett@users.noreply.github.com>
---
 docs-mslearn/toolkit/changelog.md                             | 1 +
 src/power-bi/kql/Shared.Dataset/definition/expressions.tmdl   | 2 +-
 .../kql/Shared.Dataset/definition/tables/StorageData.tmdl     | 2 +-
 .../storage/Shared.Dataset/definition/expressions.tmdl        | 4 ++--
 .../storage/Shared.Dataset/definition/tables/StorageData.tmdl | 2 +-
 5 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/docs-mslearn/toolkit/changelog.md b/docs-mslearn/toolkit/changelog.md
index 7c5d94e4b..f27219854 100644
--- a/docs-mslearn/toolkit/changelog.md
+++ b/docs-mslearn/toolkit/changelog.md
@@ -45,6 +45,7 @@ The following section lists features and enhancements that are currently in deve
 
 - **Fixed**
   - Fixed tag expansion in Power BI reports when tag names contain special characters like colons.
+  - Fixed "Number of Months" parameter calculation that was excluding the first 5 days of data when set to 3 months ([#1833](https://github.com/microsoft/finops-toolkit/issues/1833)).
 
 ### [FinOps hubs](hubs/finops-hubs-overview.md) v13
 
diff --git a/src/power-bi/kql/Shared.Dataset/definition/expressions.tmdl b/src/power-bi/kql/Shared.Dataset/definition/expressions.tmdl
index 8462dbca5..81cf35cf5 100644
--- a/src/power-bi/kql/Shared.Dataset/definition/expressions.tmdl
+++ b/src/power-bi/kql/Shared.Dataset/definition/expressions.tmdl
@@ -22,7 +22,7 @@ expression '▶️  START HERE' = ```
 				    DateEnd = null,
 				    DateStart = null,
 				    DateMonths = #"Number of Months",
-				    DateStartEffective = if DateStart <> null and DateStart <> "" then DateStart else Date.AddMonths(if DateEnd <> null and DateEnd <> "" then DateEnd else Date.AddMonths(Date.StartOfMonth(DateTime.LocalNow()), 1), -DateMonths+1),
+				    DateStartEffective = if DateStart <> null and DateStart <> "" then DateStart else Date.AddMonths(if DateEnd <> null and DateEnd <> "" then DateEnd else Date.AddMonths(Date.StartOfMonth(DateTime.LocalNow()), 1), -DateMonths),
 				    _formatDate = (d) => try DateTime.ToText(d, [Format="MMM d, yyyy"]) otherwise d,
 				    DateStartFormat = 
 				        if (DateStart = null or DateStart = "") and (DateMonths = null or DateMonths < 1) then "*"
diff --git a/src/power-bi/kql/Shared.Dataset/definition/tables/StorageData.tmdl b/src/power-bi/kql/Shared.Dataset/definition/tables/StorageData.tmdl
index 71037ccca..7c617c9a1 100644
--- a/src/power-bi/kql/Shared.Dataset/definition/tables/StorageData.tmdl
+++ b/src/power-bi/kql/Shared.Dataset/definition/tables/StorageData.tmdl
@@ -266,7 +266,7 @@ table StorageData
 					end   = if RangeEnd <> null then Date.From(RangeEnd, Culture.Current) else null,
 					start = 
 						if RangeStart <> null then Date.From(RangeStart, Culture.Current)
-						else if #"Number of Months" <> null and #"Number of Months" > 0 then Date.AddMonths(if end <> null then end else Date.StartOfMonth(Date.From(DateTime.LocalNow())), -(#"Number of Months"+1))
+						else if #"Number of Months" <> null and #"Number of Months" > 0 then Date.AddMonths(if end <> null then end else Date.StartOfMonth(Date.From(DateTime.LocalNow())), -#"Number of Months")
 						else null,
 					FilterFilesByDate =
 						if start = null and end = null then InitialDetails
diff --git a/src/power-bi/storage/Shared.Dataset/definition/expressions.tmdl b/src/power-bi/storage/Shared.Dataset/definition/expressions.tmdl
index b6685af8f..98873d2dc 100644
--- a/src/power-bi/storage/Shared.Dataset/definition/expressions.tmdl
+++ b/src/power-bi/storage/Shared.Dataset/definition/expressions.tmdl
@@ -58,7 +58,7 @@ expression '▶️  START HERE' = ```
 				    DateEnd = RangeEnd,
 				    DateStart = RangeStart,
 				    DateMonths = #"Number of Months",
-				    DateStartEffective = if DateStart <> null and DateStart <> "" then DateStart else Date.AddMonths(if DateEnd <> null and DateEnd <> "" then DateEnd else Date.AddMonths(Date.StartOfMonth(DateTime.LocalNow()), 1), -DateMonths+1),
+				    DateStartEffective = if DateStart <> null and DateStart <> "" then DateStart else Date.AddMonths(if DateEnd <> null and DateEnd <> "" then DateEnd else Date.AddMonths(Date.StartOfMonth(DateTime.LocalNow()), 1), -DateMonths),
 				    _formatDate = (d) => try DateTime.ToText(d, [Format="MMM d, yyyy"]) otherwise d,
 				    DateStartFormat = 
 				        if (DateStart = null or DateStart = "") and (DateMonths = null or DateMonths < 1) then "*"
@@ -127,7 +127,7 @@ expression ftk_Storage = ```
 			end   = if RangeEnd <> null then Date.From(RangeEnd, Culture.Current) else null,
 			start = 
 				if RangeStart <> null then Date.From(RangeStart, Culture.Current)
-				else if #"Number of Months" <> null and #"Number of Months" > 0 then Date.AddMonths(if end <> null then end else Date.StartOfMonth(Date.From(DateTime.LocalNow())), -(#"Number of Months"+1))
+				else if #"Number of Months" <> null and #"Number of Months" > 0 then Date.AddMonths(if end <> null then end else Date.StartOfMonth(Date.From(DateTime.LocalNow())), -#"Number of Months")
 				else null,
 			data = if datasetType <> null and datasetType <> "" then Text.Lower(datasetType) else "focuscost",
 		
diff --git a/src/power-bi/storage/Shared.Dataset/definition/tables/StorageData.tmdl b/src/power-bi/storage/Shared.Dataset/definition/tables/StorageData.tmdl
index 43eb716b3..8c1d26051 100644
--- a/src/power-bi/storage/Shared.Dataset/definition/tables/StorageData.tmdl
+++ b/src/power-bi/storage/Shared.Dataset/definition/tables/StorageData.tmdl
@@ -266,7 +266,7 @@ table StorageData
 					end   = if RangeEnd <> null then Date.From(RangeEnd, Culture.Current) else null,
 					start = 
 						if RangeStart <> null then Date.From(RangeStart, Culture.Current)
-						else if #"Number of Months" <> null and #"Number of Months" > 0 then Date.AddMonths(if end <> null then end else Date.StartOfMonth(Date.From(DateTime.LocalNow())), -(#"Number of Months"+1))
+						else if #"Number of Months" <> null and #"Number of Months" > 0 then Date.AddMonths(if end <> null then end else Date.StartOfMonth(Date.From(DateTime.LocalNow())), -#"Number of Months")
 						else null,
 					FilterFilesByDate =
 						if start = null and end = null then InitialDetails