diff --git a/CHANGELOG.md b/CHANGELOG.md
index afa7d72fa76..31d75feb340 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,12 @@ and this project adheres to
 
 ### Added
 
+- Report monthly active users (MAU) — distinct users active in the trailing 30
+  days — in the usage tracker submission, alongside the existing 90-day active
+  user count. Reported at both instance and project level, and bumps the usage
+  report schema to version 3.
+  [#4826](https://github.com/OpenFn/lightning/issues/4826)
+
 ### Changed
 
 - Stop reporting expected credential-resolution failures (OAuth re-auth needed,
diff --git a/lib/lightning/usage_tracking/project_metrics_service.ex b/lib/lightning/usage_tracking/project_metrics_service.ex
index e1f6ff4eea9..d24dea7eb17 100644
--- a/lib/lightning/usage_tracking/project_metrics_service.ex
+++ b/lib/lightning/usage_tracking/project_metrics_service.ex
@@ -27,6 +27,8 @@ defmodule Lightning.UsageTracking.ProjectMetricsService do
 
     %{
       no_of_active_users: UserService.no_of_active_users(date, users),
+      no_of_monthly_active_users:
+        UserService.no_of_monthly_active_users(date, users),
       no_of_users: UserService.no_of_users(date, users),
       workflows: instrument_workflows(project, cleartext_enabled, date)
     }
diff --git a/lib/lightning/usage_tracking/report_data.ex b/lib/lightning/usage_tracking/report_data.ex
index 82a3644f357..e59531987fa 100644
--- a/lib/lightning/usage_tracking/report_data.ex
+++ b/lib/lightning/usage_tracking/report_data.ex
@@ -15,7 +15,7 @@ defmodule Lightning.UsageTracking.ReportData do
       instance: instrument_instance(configuration, cleartext_enabled, date),
       projects: instrument_projects(cleartext_enabled, date),
       report_date: date,
-      version: "2"
+      version: "3"
     }
   end
 
@@ -26,6 +26,7 @@ defmodule Lightning.UsageTracking.ReportData do
     |> instrument_identity(cleartext_enabled)
     |> Map.merge(%{
       no_of_active_users: UserService.no_of_active_users(date),
+      no_of_monthly_active_users: UserService.no_of_monthly_active_users(date),
       no_of_users: UserService.no_of_users(date),
       operating_system: operating_system_name(),
       version: UsageTracking.lightning_version()
diff --git a/lib/lightning/usage_tracking/user_queries.ex b/lib/lightning/usage_tracking/user_queries.ex
index 524cc1c58e7..a010808c42d 100644
--- a/lib/lightning/usage_tracking/user_queries.ex
+++ b/lib/lightning/usage_tracking/user_queries.ex
@@ -9,6 +9,12 @@ defmodule Lightning.UsageTracking.UserQueries do
   alias Lightning.Accounts.User
   alias Lightning.Accounts.UserToken
 
+  # Trailing window (in days) used for the two active-user metrics. The 90-day
+  # figure is the original `no_of_active_users` series; the 30-day figure backs
+  # the standard SaaS "monthly active users" (MAU) metric.
+  @active_window_days 90
+  @monthly_active_window_days 30
+
   def existing_users(date) do
     report_time = report_date_as_time(date)
 
@@ -16,17 +22,32 @@ defmodule Lightning.UsageTracking.UserQueries do
   end
 
   def existing_users(date, user_list) do
-    list_ids = user_list |> Enum.map(& &1.id)
-
-    from eu in existing_users(date), where: eu.id in ^list_ids
+    existing_users(date) |> filter_by_users(user_list)
   end
 
   def active_users(date) do
+    active_users_within(date, @active_window_days)
+  end
+
+  def active_users(date, user_list) do
+    active_users_within(date, @active_window_days) |> filter_by_users(user_list)
+  end
+
+  def monthly_active_users(date) do
+    active_users_within(date, @monthly_active_window_days)
+  end
+
+  def monthly_active_users(date, user_list) do
+    active_users_within(date, @monthly_active_window_days)
+    |> filter_by_users(user_list)
+  end
+
+  defp active_users_within(date, window_days) do
     report_time = report_date_as_time(date)
 
     {:ok, threshold_time, _offset} =
       date
-      |> Date.add(-90)
+      |> Date.add(-window_days)
       |> then(&"#{&1}T23:59:59Z")
       |> DateTime.from_iso8601()
 
@@ -38,10 +59,10 @@ defmodule Lightning.UsageTracking.UserQueries do
       where: ut.inserted_at > ^threshold_time and ut.inserted_at <= ^report_time
   end
 
-  def active_users(date, user_list) do
+  defp filter_by_users(query, user_list) do
     list_ids = user_list |> Enum.map(& &1.id)
 
-    from au in active_users(date), where: au.id in ^list_ids
+    from u in query, where: u.id in ^list_ids
   end
 
   defp report_date_as_time(date) do
diff --git a/lib/lightning/usage_tracking/user_service.ex b/lib/lightning/usage_tracking/user_service.ex
index e1318d67769..a038f8cd0b6 100644
--- a/lib/lightning/usage_tracking/user_service.ex
+++ b/lib/lightning/usage_tracking/user_service.ex
@@ -22,4 +22,12 @@ defmodule Lightning.UsageTracking.UserService do
   def no_of_active_users(date, user_list) do
     UserQueries.active_users(date, user_list) |> Repo.aggregate(:count)
   end
+
+  def no_of_monthly_active_users(date) do
+    UserQueries.monthly_active_users(date) |> Repo.aggregate(:count)
+  end
+
+  def no_of_monthly_active_users(date, user_list) do
+    UserQueries.monthly_active_users(date, user_list) |> Repo.aggregate(:count)
+  end
 end
diff --git a/test/lightning/usage_tracking/project_metrics_service_test.exs b/test/lightning/usage_tracking/project_metrics_service_test.exs
index ed815e9cf19..41a2c135bff 100644
--- a/test/lightning/usage_tracking/project_metrics_service_test.exs
+++ b/test/lightning/usage_tracking/project_metrics_service_test.exs
@@ -136,6 +136,50 @@ defmodule Lightning.UsageTracking.ProjectMetricsServiceTest do
              } = ProjectMetricsService.generate_metrics(project, enabled, date)
     end
 
+    test "includes the number of monthly active users (trailing 30 days)", %{
+      date: date,
+      enabled: enabled,
+      project: project
+    } do
+      # The project's active users last logged in at 2023-11-08, which is
+      # within the 90-day window but outside the 30-day monthly window.
+      assert %{
+               no_of_monthly_active_users: 0
+             } = ProjectMetricsService.generate_metrics(project, enabled, date)
+    end
+
+    test "counts project users active within the trailing 30 days", %{
+      date: date,
+      enabled: enabled
+    } do
+      {:ok, within_30_days, _offset} =
+        DateTime.from_iso8601("#{Date.add(date, -10)}T10:00:00Z")
+
+      project =
+        insert(:project,
+          project_users: [
+            build(:project_user,
+              user: fn ->
+                user = insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+                insert(:user_token,
+                  context: "session",
+                  user: user,
+                  inserted_at: within_30_days
+                )
+
+                user
+              end
+            )
+          ]
+        )
+        |> Repo.preload([:users, workflows: [:jobs, :runs]])
+
+      assert %{
+               no_of_monthly_active_users: 1
+             } = ProjectMetricsService.generate_metrics(project, enabled, date)
+    end
+
     test "includes data for workflows existing on or before date", %{
       date: date,
       eligible_workflow_1: eligible_workflow_1,
diff --git a/test/lightning/usage_tracking/report_data_test.exs b/test/lightning/usage_tracking/report_data_test.exs
index 93e1a9e86af..11c06af59b1 100644
--- a/test/lightning/usage_tracking/report_data_test.exs
+++ b/test/lightning/usage_tracking/report_data_test.exs
@@ -144,6 +144,39 @@ defmodule Lightning.UsageTracking.ReportDataTest do
              } = ReportData.generate(report_config, enabled, date)
     end
 
+    test "includes the number of monthly active users (trailing 30 days)", %{
+      cleartext_enabled: enabled,
+      config: report_config,
+      date: date
+    } do
+      {:ok, within_30_days, _offset} =
+        DateTime.from_iso8601("#{Date.add(date, -29)}T10:00:00Z")
+
+      {:ok, within_90_but_not_30_days, _offset} =
+        DateTime.from_iso8601("#{Date.add(date, -45)}T10:00:00Z")
+
+      monthly_active_user = insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      insert(:user_token,
+        context: "session",
+        inserted_at: within_30_days,
+        user: monthly_active_user
+      )
+
+      quarterly_only_user = insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      insert(:user_token,
+        context: "session",
+        inserted_at: within_90_but_not_30_days,
+        user: quarterly_only_user
+      )
+
+      # The 90-day window counts both; only one is active within 30 days.
+      assert %{
+               instance: %{no_of_active_users: 2, no_of_monthly_active_users: 1}
+             } = ReportData.generate(report_config, enabled, date)
+    end
+
     test "includes the operating system details", %{
       cleartext_enabled: enabled,
       config: report_config,
@@ -196,7 +229,7 @@ defmodule Lightning.UsageTracking.ReportDataTest do
       config: report_config,
       date: date
     } do
-      assert %{version: "2"} = ReportData.generate(report_config, enabled, date)
+      assert %{version: "3"} = ReportData.generate(report_config, enabled, date)
     end
 
     test "indicates the applicable report date", %{
@@ -399,7 +432,7 @@ defmodule Lightning.UsageTracking.ReportDataTest do
       config: report_config,
       date: date
     } do
-      assert %{version: "2"} = ReportData.generate(report_config, enabled, date)
+      assert %{version: "3"} = ReportData.generate(report_config, enabled, date)
     end
 
     test "indicates the applicable report date", %{
diff --git a/test/lightning/usage_tracking/user_queries_test.exs b/test/lightning/usage_tracking/user_queries_test.exs
index 983a92445f4..4163f818873 100644
--- a/test/lightning/usage_tracking/user_queries_test.exs
+++ b/test/lightning/usage_tracking/user_queries_test.exs
@@ -231,6 +231,147 @@ defmodule Lightning.UsageTracking.UserQueriesTest do
     end
   end
 
+  describe "monthly_active_users/1" do
+    test "returns users that have logged in in the last 30 days" do
+      user_within_window =
+        insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      _active_token =
+        insert(
+          :user_token,
+          context: "session",
+          inserted_at: ~U[2024-01-07 00:00:00Z],
+          user: user_within_window
+        )
+
+      user_on_report_date =
+        insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      _active_token =
+        insert(
+          :user_token,
+          context: "session",
+          inserted_at: ~U[2024-02-05 23:59:59Z],
+          user: user_on_report_date
+        )
+
+      user_older_than_30_days =
+        insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      _ineligible_token_older_than_30_days =
+        insert(
+          :user_token,
+          context: "session",
+          inserted_at: ~U[2024-01-06 23:59:59Z],
+          user: user_older_than_30_days
+        )
+
+      user_newer_than_report_date =
+        insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      _ineligible_token_newer_than_report_date =
+        insert(
+          :user_token,
+          context: "session",
+          inserted_at: ~U[2024-02-06 00:00:01Z],
+          user: user_newer_than_report_date
+        )
+
+      user_with_non_session_token =
+        insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      _ineligible_token_not_session =
+        insert(
+          :user_token,
+          context: "api",
+          inserted_at: ~U[2024-02-05 00:00:01Z],
+          user: user_with_non_session_token
+        )
+
+      result = UserQueries.monthly_active_users(@date) |> Repo.all()
+
+      assert(result |> contains(user_within_window))
+      assert(result |> contains(user_on_report_date))
+      refute(result |> contains(user_older_than_30_days))
+      refute(result |> contains(user_newer_than_report_date))
+      refute(result |> contains(user_with_non_session_token))
+    end
+
+    test "if user has more than one token, only includes user once" do
+      user =
+        insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      _active_token_1 =
+        insert(
+          :user_token,
+          context: "session",
+          inserted_at: ~U[2024-01-07 00:00:00Z],
+          user: user
+        )
+
+      _active_token_2 =
+        insert(
+          :user_token,
+          context: "session",
+          inserted_at: ~U[2024-01-07 00:00:01Z],
+          user: user
+        )
+
+      result = UserQueries.monthly_active_users(@date) |> Repo.all()
+
+      assert(result |> contains(user))
+      assert(length(result) == 1)
+    end
+  end
+
+  describe "monthly_active_users/2" do
+    test "returns subset of user list that have logged in the last 30 days" do
+      user_in_list_within_window =
+        insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      _active_token =
+        insert(
+          :user_token,
+          context: "session",
+          inserted_at: ~U[2024-01-07 00:00:00Z],
+          user: user_in_list_within_window
+        )
+
+      user_not_in_list =
+        insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      _active_token =
+        insert(
+          :user_token,
+          context: "session",
+          inserted_at: ~U[2024-01-07 00:00:00Z],
+          user: user_not_in_list
+        )
+
+      user_in_list_older_than_30_days =
+        insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      _ineligible_token_older_than_30_days =
+        insert(
+          :user_token,
+          context: "session",
+          inserted_at: ~U[2024-01-06 23:59:59Z],
+          user: user_in_list_older_than_30_days
+        )
+
+      user_list = [
+        user_in_list_within_window,
+        user_in_list_older_than_30_days
+      ]
+
+      result = UserQueries.monthly_active_users(@date, user_list) |> Repo.all()
+
+      assert(result |> contains(user_in_list_within_window))
+      refute(result |> contains(user_not_in_list))
+      refute(result |> contains(user_in_list_older_than_30_days))
+    end
+  end
+
   defp contains(result, desired_user) do
     result |> Enum.find(fn user -> user.id == desired_user.id end)
   end
diff --git a/test/lightning/usage_tracking/user_service_test.exs b/test/lightning/usage_tracking/user_service_test.exs
index 39e5030237f..0f5eead055a 100644
--- a/test/lightning/usage_tracking/user_service_test.exs
+++ b/test/lightning/usage_tracking/user_service_test.exs
@@ -189,4 +189,71 @@ defmodule Lightning.UsageTracking.UserServiceTest do
       assert UserService.no_of_active_users(@date, user_list) == 2
     end
   end
+
+  describe ".no_of_monthly_active_users/1" do
+    test "counts users active within the trailing 30 days" do
+      {:ok, within_threshold_time, _offset} =
+        DateTime.from_iso8601("#{Date.add(@date, -29)}T10:00:00Z")
+
+      {:ok, outside_threshold_time, _offset} =
+        DateTime.from_iso8601("#{Date.add(@date, -30)}T10:00:00Z")
+
+      user_within_window = insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      insert(:user_token,
+        context: "session",
+        inserted_at: within_threshold_time,
+        user: user_within_window
+      )
+
+      user_outside_window = insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      insert(:user_token,
+        context: "session",
+        inserted_at: outside_threshold_time,
+        user: user_outside_window
+      )
+
+      assert UserService.no_of_monthly_active_users(@date) == 1
+    end
+  end
+
+  describe ".no_of_monthly_active_users/2" do
+    test "counts the active subset of the user list within the trailing 30 days" do
+      {:ok, within_threshold_time, _offset} =
+        DateTime.from_iso8601("#{Date.add(@date, -29)}T10:00:00Z")
+
+      {:ok, outside_threshold_time, _offset} =
+        DateTime.from_iso8601("#{Date.add(@date, -30)}T10:00:00Z")
+
+      user_in_list_active = insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      insert(:user_token,
+        context: "session",
+        inserted_at: within_threshold_time,
+        user: user_in_list_active
+      )
+
+      user_not_in_list = insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      insert(:user_token,
+        context: "session",
+        inserted_at: within_threshold_time,
+        user: user_not_in_list
+      )
+
+      user_in_list_inactive =
+        insert(:user, inserted_at: ~U[2024-02-04 01:00:00Z])
+
+      insert(:user_token,
+        context: "session",
+        inserted_at: outside_threshold_time,
+        user: user_in_list_inactive
+      )
+
+      user_list = [user_in_list_active, user_in_list_inactive]
+
+      assert UserService.no_of_monthly_active_users(@date, user_list) == 1
+    end
+  end
 end