diff --git a/application/models/crm/Konto_model.php b/application/models/crm/Konto_model.php
index 286d3189e..eae38a49e 100644
--- a/application/models/crm/Konto_model.php
+++ b/application/models/crm/Konto_model.php
@@ -11,4 +11,58 @@ class Konto_model extends DB_Model
 		$this->dbTable = 'public.tbl_konto';
 		$this->pk = 'buchungsnr';
 	}
+
+	/**
+	 * Sets a Payment as paid
+	 */
+	public function setPaid($buchungsnr)
+	{
+		// get payment
+		$buchungResult =  $this->loadWhere(array('buchungsnr' => $buchungsnr));
+
+		if(isSuccess($buchungResult) && hasData($buchungResult))
+		{
+			// get already paid amount
+			$this->addSelect('sum(betrag) as bezahlt');
+			$this->addGroupBy('buchungsnr_verweis');
+			$buchungVerweisResult =  $this->loadWhere(array('buchungsnr_verweis' => $buchungsnr));
+
+			if(isSuccess($buchungVerweisResult))
+			{
+				if(hasData($buchungVerweisResult))
+				{
+					$betragBezahltResult = getData($buchungVerweisResult);
+					$betragBezahlt = $betragBezahltResult->bezahlt;
+				}
+				else
+					$betragBezahlt = 0;
+
+				$buchung = getData($buchungResult);
+				$buchung = $buchung[0];
+
+				// calculate open amount
+				$betragOffen = $betragBezahlt - $buchung->betrag*(-1);
+
+				$data = array(
+					'person_id' => $buchung->person_id,
+					'studiengang_kz' => $buchung->studiengang_kz,
+					'studiensemester_kurzbz' => $buchung->studiensemester_kurzbz,
+					'buchungsnr_verweis' => $buchungsnr,
+					'betrag' => $betragOffen*(-1),
+					'buchungsdatum' => date('Y-m-d'),
+					'buchungstext' => $buchung->buchungstext,
+					'insertamum' => date('Y-m-d H:i:s'),
+					'insertvon' => '',
+					'buchungstyp_kurzbz' => $buchung->buchungstyp_kurzbz,
+				);
+				return $this->insert($data);
+			}
+			else
+				return error('Failed to load Payment');
+		}
+		else
+		{
+			return error('Failed to load Payment');
+		}
+	}
 }