From c8d14cae0977a0614dc6412e6903dd757195de2f Mon Sep 17 00:00:00 2001
From: Matt Fiddaman <github@m.fiddaman.uk>
Date: Tue, 4 Mar 2025 11:33:29 +0000
Subject: [PATCH] improve summary report monthly average calculation (#4302)

---
 .../reports/spreadsheets/summary-spreadsheet.ts    | 14 +++++++++++---
 upcoming-release-notes/4302.md                     |  6 ++++++
 2 files changed, 17 insertions(+), 3 deletions(-)
 create mode 100644 upcoming-release-notes/4302.md

diff --git a/packages/desktop-client/src/components/reports/spreadsheets/summary-spreadsheet.ts b/packages/desktop-client/src/components/reports/spreadsheets/summary-spreadsheet.ts
index 1846b66b6a8..68fa418c09d 100644
--- a/packages/desktop-client/src/components/reports/spreadsheets/summary-spreadsheet.ts
+++ b/packages/desktop-client/src/components/reports/spreadsheets/summary-spreadsheet.ts
@@ -48,7 +48,10 @@ export function summarySpreadsheet(
       );
 
       endDay = d.parse(
-        monthUtils.lastDayOfMonth(end),
+        monthUtils.getMonth(end) ===
+          monthUtils.getMonth(monthUtils.currentDay())
+          ? monthUtils.currentDay()
+          : monthUtils.lastDayOfMonth(end),
         'yyyy-MM-dd',
         new Date(),
       );
@@ -196,13 +199,18 @@ function calculatePerMonth(
     amount: monthlyData[d.format(m, 'yyyy-MM')] || 0,
   }));
 
+  const lastMonth = months.at(-1)!;
+  const dayOfMonth = lastMonth.getDate();
+  const daysInMonth = monthUtils.getDay(monthUtils.lastDayOfMonth(lastMonth));
+  const numMonths = months.length - 1 + dayOfMonth / daysInMonth;
+
   const totalAmount = monthsSum.reduce((sum, month) => sum + month.amount, 0);
-  const averageAmountPerMonth = totalAmount / months.length;
+  const averageAmountPerMonth = totalAmount / numMonths;
 
   return {
     total: averageAmountPerMonth / 100,
     dividend: totalAmount / 100,
-    divisor: months.length,
+    divisor: numMonths,
   };
 }
 
diff --git a/upcoming-release-notes/4302.md b/upcoming-release-notes/4302.md
new file mode 100644
index 00000000000..5ef11bf8e6d
--- /dev/null
+++ b/upcoming-release-notes/4302.md
@@ -0,0 +1,6 @@
+---
+category: Enhancements
+authors: [matt-fidd]
+---
+
+Improve summary report monthly average calculation