diff --git a/changelog/27426.txt b/changelog/27426.txt
new file mode 100644
index 0000000000..ac18d43862
--- /dev/null
+++ b/changelog/27426.txt
@@ -0,0 +1,4 @@
+```release-note:change
+activity log: Deprecates the current_billing_period field for /sys/internal/counters/activity. The default start time
+will automatically be set the billing period start date.
+```
\ No newline at end of file
diff --git a/vault/logical_system_activity.go b/vault/logical_system_activity.go
index 8eeeb24ad3..38674be000 100644
--- a/vault/logical_system_activity.go
+++ b/vault/logical_system_activity.go
@@ -20,6 +20,11 @@ import (
 // defaultToRetentionMonthsMaxWarning is a warning message for setting the max retention_months value when retention_months value is more than activityLogMaximumRetentionMonths
 var defaultToRetentionMonthsMaxWarning = fmt.Sprintf("retention_months cannot be greater than %d; capped to %d.", activityLogMaximumRetentionMonths, activityLogMaximumRetentionMonths)
 
+const (
+	// WarningCurrentBillingPeriodDeprecated is a warning string that is used to indicate that the current_billing_period field, as the default start time will automatically be the billing period start date
+	WarningCurrentBillingPeriodDeprecated = "current_billing_period is deprecated; unless otherwise specified, all requests will default to the current billing period"
+)
+
 // activityQueryPath is available in every namespace
 func (b *SystemBackend) activityQueryPath() *framework.Path {
 	return &framework.Path{
@@ -33,6 +38,7 @@ func (b *SystemBackend) activityQueryPath() *framework.Path {
 
 		Fields: map[string]*framework.FieldSchema{
 			"current_billing_period": {
+				Deprecated:  true,
 				Type:        framework.TypeBool,
 				Description: "Query utilization for configured billing period",
 			},
@@ -254,15 +260,16 @@ func (b *SystemBackend) handleClientMetricQuery(ctx context.Context, req *logica
 		return logical.ErrorResponse("no activity log present"), nil
 	}
 
-	if d.Get("current_billing_period").(bool) {
-		startTime = b.Core.BillingStart()
-		endTime = time.Now().UTC()
-	} else {
-		var err error
-		startTime, endTime, err = parseStartEndTimes(a, d, b.Core.BillingStart())
-		if err != nil {
-			return logical.ErrorResponse(err.Error()), nil
-		}
+	warnings := make([]string, 0)
+
+	if _, ok := d.GetOk("current_billing_period"); ok {
+		warnings = append(warnings, WarningCurrentBillingPeriodDeprecated)
+	}
+
+	var err error
+	startTime, endTime, err = parseStartEndTimes(a, d, b.Core.BillingStart())
+	if err != nil {
+		return logical.ErrorResponse(err.Error()), nil
 	}
 
 	var limitNamespaces int
@@ -275,12 +282,15 @@ func (b *SystemBackend) handleClientMetricQuery(ctx context.Context, req *logica
 		return nil, err
 	}
 	if results == nil {
-		resp204, err := logical.RespondWithStatusCode(nil, req, http.StatusNoContent)
+		resp204, err := logical.RespondWithStatusCode(&logical.Response{
+			Warnings: warnings,
+		}, req, http.StatusNoContent)
 		return resp204, err
 	}
 
 	return &logical.Response{
-		Data: results,
+		Warnings: warnings,
+		Data:     results,
 	}, nil
 }
 
diff --git a/website/content/api-docs/system/internal-counters.mdx b/website/content/api-docs/system/internal-counters.mdx
index 69be0d763d..6e12f44c6f 100644
--- a/website/content/api-docs/system/internal-counters.mdx
+++ b/website/content/api-docs/system/internal-counters.mdx
@@ -352,7 +352,7 @@ This endpoint was added in Vault 1.6.
 - `limit_namespaces` `(int, optional)` - Controls the total number of by_namespace data returned. This can
    be used to return the client counts for the specified number of namespaces having highest activity.
    If no `limit_namespaces` parameter is specified, client counts for all namespaces in specified usage period is returned.
-- `current_billing_period` `(bool, optional)` - Uses the builtin billing start
+- `current_billing_period` `(bool, optional)` - **DEPRECATED** Uses the builtin billing start
   timestamp as `start_time` and the current time as the `end_time`, returning a
   response with the current billing period information without having to
   explicitly provide a start and end time.
diff --git a/website/content/docs/upgrading/upgrade-to-1.18.x.mdx b/website/content/docs/upgrading/upgrade-to-1.18.x.mdx
index d111c6c9c9..28e7f4583a 100644
--- a/website/content/docs/upgrading/upgrade-to-1.18.x.mdx
+++ b/website/content/docs/upgrading/upgrade-to-1.18.x.mdx
@@ -16,6 +16,8 @@ Vault 1.17. **Please read carefully**.
 
 ### Activity Log Changes
 
+#### Default Activity Log Querying Period
+
 The field `default_report_months` can no longer be configured or read. Any previously set values
 will be ignored by the system.
 
@@ -36,3 +38,22 @@ WARNING! The following warnings were returned from Vault:
 ```
 
 </CodeBlockConfig>
+
+
+The `current_billing_period` toggle for `/sys/internal/counters/activity` is also deprecated, as this will be set
+true by default.
+
+Attempts to set `current_billing_period` will result in the following warning from Vault:
+
+<CodeBlockConfig hideClipboard>
+
+```shell-session
+
+WARNING! The following warnings were returned from Vault:
+
+  * current_billing_period is deprecated; unless otherwise specified, all requests will default to the current billing period
+
+
+```
+
+</CodeBlockConfig>