diff --git a/app/Models/Service.php b/app/Models/Service.php
index 6283153..184c461 100644
--- a/app/Models/Service.php
+++ b/app/Models/Service.php
@@ -826,10 +826,13 @@ class Service extends Model implements IDs
 	/**
 	 * Work out when this service has been paid to.
 	 *
-	 * @return Carbon
+	 * @return Carbon|null
 	 */
-	public function getPaidToAttribute(): Carbon
+	public function getPaidToAttribute(): ?Carbon
 	{
+		if (! $this->invoices->count())
+			return NULL;
+
 		foreach ($this->invoices->reverse() as $o)
 			if ($o->due == 0)
 				break;