diff --git a/application/controllers/api/frontend/v1/stv/Konto.php b/application/controllers/api/frontend/v1/stv/Konto.php
index 12892d2f7..002d84766 100644
--- a/application/controllers/api/frontend/v1/stv/Konto.php
+++ b/application/controllers/api/frontend/v1/stv/Konto.php
@@ -39,7 +39,9 @@ class Konto extends FHCAPI_Controller
 			'getBuchungstypen' => 'student/stammdaten:r', // alle?
 			'checkDoubles' => ['admin:r', 'assistenz:r'],
 			'insert' => ['admin:w', 'assistenz:w'],
-			'update' => ['admin:w', 'assistenz:w']
+			'counter' => ['admin:w', 'assistenz:w'],
+			'update' => ['admin:w', 'assistenz:w'],
+			'delete' => ['admin:w', 'assistenz:w']
 		]);
 
 		// Load models
@@ -64,11 +66,12 @@ class Konto extends FHCAPI_Controller
 		$this->load->library('form_validation');
 
 		$person_id = $this->input->post('person_id');
-		if (!$person_id || !is_array($person_id))
+		if (!$person_id || !is_array($person_id)) {
 			$this->form_validation->set_rules('person_id', 'Person ID', 'required');
 
-		if (!$this->form_validation->run())
-			$this->terminateWithValidationErrors($this->form_validation->error_array());
+			if (!$this->form_validation->run())
+				$this->terminateWithValidationErrors($this->form_validation->error_array());
+		}
 
 
 		$studiengang_kz = $this->input->post('studiengang_kz');
@@ -237,8 +240,8 @@ class Konto extends FHCAPI_Controller
 			'anmerkung'
 		];
 		$data = [
-			'updateamum' => date('c'),
-			'updatevon' => getAuthUID()
+			'insertamum' => date('c'),
+			'insertvon' => getAuthUID()
 		];
 		foreach ($allowed as $field)
 			if ($this->input->post($field) !== null)
@@ -251,20 +254,145 @@ class Konto extends FHCAPI_Controller
 		$result = [];
 		foreach ($person_ids as $person_id) {
 			$id = $this->KontoModel->insert(array_merge($data, ['person_id' => $person_id]));
-			if (isError($id))
-				$this->addError(getError($id), self::ERROR_TYPE_GENERAL);
-			else {
+			if (isError($id)) {
+				$this->addError(getError($id), self::ERROR_TYPE_DB);
+			} else {
 				$data = $this->KontoModel->withAdditionalInfo()->load(getData($id));
 				if (isError($data))
-					$this->addError(getError($data), self::ERROR_TYPE_GENERAL);
+					$this->addError(getError($data), self::ERROR_TYPE_DB);
 				else
-					$result[] = getData($data);
+					$result[] = current(getData($data));
 			}
 		}
 
 		if ($result)
 			$this->terminateWithSuccess($result);
-		// NOTE(chris): else there should already be error in the return object
+
+		$this->output->set_status_header(REST_Controller::HTTP_INTERNAL_SERVER_ERROR);
+	}
+
+	/**
+	 * Save Counter Buchung
+	 *
+	 * @return void
+	 */
+	public function counter()
+	{
+		$this->load->library('form_validation');
+
+		$buchungsnrs = $this->input->post('buchungsnr');
+
+		if (!$buchungsnrs || !is_array($buchungsnrs)) {
+			$buchungsnrs = $buchungsnrs ? [$buchungsnrs] : [];
+			$this->form_validation->set_rules('buchungsnr', 'Buchungsnr', 'required');
+		}
+		$this->form_validation->set_rules('buchungsdatum', 'Buchungsdatum', 'is_valid_date');
+
+		if (!$this->form_validation->run())
+			$this->terminateWithValidationErrors($this->form_validation->error_array());
+
+		$data = [];
+		$rules = [];
+		foreach ($buchungsnrs as $k => $buchungsnr) {
+			$result = $this->KontoModel->load($buchungsnr);
+			if (isError($result)) {
+				$rules[] = [
+					'field' => 'buchung[' . $k . ']',
+					'label' => 'Buchung #' . $buchungsnr,
+					'rules' => 'required',
+					'errors' => [
+						'required' => getError($result)
+					]
+				];
+			} elseif (!hasData($result)) {
+				$rules[] = [
+					'field' => 'buchung[' . $k . ']',
+					'label' => 'Buchung #' . $buchungsnr,
+					'rules' => 'required'
+				];
+			} else {
+				$data[$k] = get_object_vars(current(getData($result)));
+				$rules[] = [
+					'field' => 'buchung[' . $k . '][buchungsnr]',
+					'label' => 'Buchung # ' . $buchungsnr,
+					'rules' => 'required|numeric'
+				];
+				$rules[] = [
+					'field' => 'buchung[' . $k . '][studiengang_kz]',
+					'label' => 'Buchung # ' . $buchungsnr,
+					'rules' => 'required|has_permissions_for_stg[admin:rw,assistenz:rw]'
+				];
+				$rules[] = [
+					'field' => 'buchung[' . $k . '][buchungsnr_verweis]',
+					'label' => 'Buchung # ' . $buchungsnr,
+					'rules' => 'regex_match[/^$/]',
+					'errors' => [
+						'regex_match' => 'Gegenbuchungen koennen nur auf die obersten Buchungen getaetigt werden'
+					] // TODO(chris): phrase
+				];
+			}
+		}
+		
+		$this->form_validation->reset_validation();
+		$this->form_validation->set_data(['buchung' => $data]);
+		$this->form_validation->set_rules($rules);
+		
+		Events::trigger('konto_counter_validation', $this->form_validation);
+
+		if (!$this->form_validation->run())
+			$this->terminateWithValidationErrors($this->form_validation->error_array());
+
+		$buchungsdatum = $this->input->post('buchungsdatum');
+
+		$newItems = [];
+		foreach ($data as $buchung) {
+			$result = $this->KontoModel->getDifferenz($buchung['buchungsnr']);
+			if (isError($result)) {
+				$this->addError(getError($result), self::ERROR_TYPE_GENERAL);
+				continue;
+			}
+			$betrag = $result->retval;
+			if ($betrag === null) {
+				$this->addError($this->p->t(
+					'konto',
+					'Buchung #{buchungsnr} does not exist',
+					$buchung
+				), self::ERROR_TYPE_GENERAL); // TODO(chris): phrase
+				continue;
+			}
+
+
+			$result = $this->KontoModel->insert([
+				'person_id' => $buchung['person_id'],
+				'studiengang_kz' => $buchung['studiengang_kz'],
+				'studiensemester_kurzbz' => $buchung['studiensemester_kurzbz'],
+				'buchungstext' => $buchung['buchungstext'],
+				'buchungstyp_kurzbz' => $buchung['buchungstyp_kurzbz'],
+				'credit_points' => $buchung['credit_points'],
+				'zahlungsreferenz' => $buchung['zahlungsreferenz'],
+				'betrag' => $betrag,
+				'buchungsdatum' => $buchungsdatum,
+				'mahnspanne' => '0',
+				'buchungsnr_verweis' => $buchung['buchungsnr'],
+				'insertamum' => date('c'),
+				'insertvon' => getAuthUID(),
+				'anmerkung' => ''
+			]);
+			if (isError($result)) {
+				$this->addError(getError($result), self::ERROR_TYPE_GENERAL);
+				continue;
+			}
+
+			$newItems = null;
+			// TODO(chris): get as tree?
+			/*$result = $this->KontoModel->withAdditionalInfo()->load($result->retval);
+			if (!hasData($result))
+				$newItems = null;
+			elseif ($newItems !== null)
+				$newItems[] = current(getData($result));*/
+		}
+
+		$this->terminateWithSuccess($newItems);
 	}
 
 	/**
@@ -318,13 +446,63 @@ class Konto extends FHCAPI_Controller
 		if (isError($result))
 			$this->terminateWithError(getError($result), self::ERROR_TYPE_GENERAL);
 
-		$result = $this->KontoModel->withAdditionalInfo()->load($id);
+		$result = null;
+		// TODO(chris): get as tree?
+		/*$result = $this->KontoModel->withAdditionalInfo()->load($id);
 		
+		#$result = $this->getDataOrTerminateWithError($result);
+		if (isError($result))
+			$this->terminateWithError(getError($result), self::ERROR_TYPE_GENERAL);
+		$result = $result->retval;*/
+
+		$this->terminateWithSuccess($result);
+	}
+
+	/**
+	 * Delete Buchung
+	 *
+	 * @return void
+	 */
+	public function delete()
+	{
+		$this->load->library('form_validation');
+
+		$this->form_validation->set_rules('buchungsnr', 'Buchungsnr', 'required');
+
+		if (!$this->form_validation->run())
+			$this->terminateWithValidationErrors($this->form_validation->error_array());
+
+
+		$buchungsnr = $this->input->post('buchungsnr');
+
+		$result = $this->KontoModel->load($buchungsnr);
 		#$result = $this->getDataOrTerminateWithError($result);
 		if (isError($result))
 			$this->terminateWithError(getError($result), self::ERROR_TYPE_GENERAL);
 		$result = $result->retval;
 
-		$this->terminateWithSuccess($result);
+		if (!$result)
+			$this->terminateWithError('buchung not found', self::ERROR_TYPE_GENERAL); // TODO(chris): phrase
+
+		$_POST['studiengang_kz'] = current($result)->studiengang_kz;
+
+		$this->form_validation->set_rules('studiengang_kz', 'Studiengang', 'has_permissions_for_stg[admin:rw,assistenz:rw]');
+
+		Events::trigger('konto_delete_validation', $this->form_validation);
+
+		if (!$this->form_validation->run())
+			$this->terminateWithValidationErrors($this->form_validation->error_array());
+
+
+		Events::trigger('konto_delete', $buchungsnr);
+		
+		$result = $this->KontoModel->delete($buchungsnr);
+		if (isError($result)) {
+			if (getCode($result) != 42)
+				$this->terminateWithError(getError($result), self::ERROR_TYPE_GENERAL);
+			$this->terminateWithError(getError($result), self::ERROR_TYPE_GENERAL); // TODO(chris): phrase
+		}
+
+		$this->terminateWithSuccess();
 	}
 }
diff --git a/application/models/crm/Konto_model.php b/application/models/crm/Konto_model.php
index 77ae04990..6122feef0 100644
--- a/application/models/crm/Konto_model.php
+++ b/application/models/crm/Konto_model.php
@@ -15,6 +15,78 @@ class Konto_model extends DB_Model
 		$this->pk = 'buchungsnr';
 	}
 
+	/**
+	 * Insert Data into DB-Table
+	 *
+	 * @param array				$data  DataArray for Insert
+	 * @return stdClass
+	 */
+	public function insert($data, $encryptedColumns = null)
+	{
+		if (isset($data['buchungsnr_verweis']) && $data['buchungsnr_verweis'])
+			return parent::insert($data, $encryptedColumns);
+
+		$this->db->trans_begin();
+
+		$result = parent::insert($data, $encryptedColumns);
+		if (isError($result)) {
+			$this->db->trans_rollback();
+			return $result;
+		}
+
+		$buchungsnr = $result->retval;
+		// If studiengang_kz is not present in $data it will fail above since it is a not null field
+		$studiengang_kz = $data['studiengang_kz'];
+
+
+		$zahlungsreferenz = false;
+		Events::trigger('generate_zahlungsreferenz', $buchungsnr, $data, function ($value) use ($zahlungsreferenz) {
+			$zahlungsreferenz = $value;
+		});
+
+		if ($zahlungsreferenz === false) {
+			$result = $this->execQuery('SELECT UPPER(oe_kurzbz) || ? as zahlungsreferenz 
+				FROM public.tbl_studiengang 
+				WHERE studiengang_kz=?', [$buchungsnr, $studiengang_kz]);
+			if (isError($result)) {
+				$this->db->trans_rollback();
+				return $result;
+			}
+			$zahlungsreferenz = current(getData($result))->zahlungsreferenz;
+		} elseif (isError($zahlungsreferenz)) {
+			$this->db->trans_rollback();
+			return $zahlungsreferenz;
+		}
+
+
+		$result = $this->update($buchungsnr, [
+			'zahlungsreferenz' => $zahlungsreferenz
+		]);
+
+		if (isError($result)) {
+			$this->db->trans_rollback();
+			return $result;
+		}
+
+		$this->db->trans_commit();
+
+		return success($buchungsnr);
+	}
+
+	/**
+	 * Delete data from DB-Table
+	 *
+	 * @param string			$id  Primary Key for DELETE
+	 *
+	 * @return stdClass
+	 */
+	public function delete($id)
+	{
+		$this->db->where('buchungsnr_verweis', $id);
+		if ($this->db->count_all_results($this->dbTable))
+			return error('Bitte zuerst die zugeordneten Buchungen loeschen');
+		return parent::delete($id, 42);
+	}
 
 	/**
 	 * Adds additional fields to the Query
@@ -124,6 +196,37 @@ class Konto_model extends DB_Model
 		]);
 	}
 
+	/**
+	 * Berechnet den offenen Betrag einer Buchung
+	 *
+	 * @param integer		$buchungsnr
+	 *
+	 * @return stdClass
+	 */
+	public function getDifferenz($buchungsnr)
+	{
+		$this->addSelect('buchungsnr_verweis');
+		$this->db->where('buchungsnr', $buchungsnr);
+		$sql = $this->db->get_compiled_select($this->dbTable);
+
+		$this->addSelect('buchungsnr_verweis');
+		$this->db->where('buchungsnr', $buchungsnr);
+		$this->db->or_where('buchungsnr_verweis', '(' . $sql . ')', false);
+		$sql = $this->db->get_compiled_select($this->dbTable);
+
+		$this->addSelect('sum(betrag) differenz');
+		$this->db->where('buchungsnr', $buchungsnr);
+		$this->db->or_where('buchungsnr_verweis', $buchungsnr);
+		$this->db->or_where('buchungsnr', '(' . $sql . ')', false);
+
+		$result = $this->load();
+		if (isError($result))
+			return $result;
+		if (!hasData($result))
+			return success(null);
+		return success(current(getData($result))->differenz * -1);
+	}
+
 	/**
 	 * Sets a Payment as paid
 	 */
diff --git a/public/js/api/stv/konto.js b/public/js/api/stv/konto.js
index 0e4069f2c..70d5c1ef5 100644
--- a/public/js/api/stv/konto.js
+++ b/public/js/api/stv/konto.js
@@ -22,9 +22,15 @@ export default {
 	insert(data) {
 		return this.$fhcApi.post('api/frontend/v1/stv/konto/insert', data);
 	},
+	counter(data) {
+		return this.$fhcApi.post('api/frontend/v1/stv/konto/counter', data);
+	},
 	edit(data) {
 		return this.$fhcApi.post('api/frontend/v1/stv/konto/update', data);
 	},
+	delete(buchungsnr) {
+		return this.$fhcApi.post('api/frontend/v1/stv/konto/delete', {buchungsnr});
+	},
 	getBuchungstypen() {
 		return this.$fhcApi.get('api/frontend/v1/stv/konto/getBuchungstypen');
 	}
diff --git a/public/js/components/Stv/Studentenverwaltung/Details/Konto.js b/public/js/components/Stv/Studentenverwaltung/Details/Konto.js
index 849754050..7e1d7d173 100644
--- a/public/js/components/Stv/Studentenverwaltung/Details/Konto.js
+++ b/public/js/components/Stv/Studentenverwaltung/Details/Konto.js
@@ -5,7 +5,7 @@ import KontoEdit from "./Konto/Edit.js";
 
 // TODO(chris): Phrasen
 // TODO(chris): multi pers
-// TODO(chris): gegenb.(date) multi, löschen multi, best. multi(recht)
+// TODO(chris): best. multi(recht)
 
 export default {
 	components: {
@@ -24,7 +24,8 @@ export default {
 	data() {
 		return {
 			filter: false,
-			studiengang_kz: false
+			studiengang_kz: false,
+			counterdate: new Date()
 		};
 	},
 	computed: {
@@ -154,6 +155,24 @@ export default {
 					);
 					container.append(button);
 
+					button = document.createElement('button');
+					button.className = 'btn btn-outline-secondary';
+					button.innerHTML = '<i class="fa fa-trash"></i>';
+					button.addEventListener('click', evt => {
+						evt.stopPropagation();
+						this.$fhcAlert
+							.confirmDelete()
+							.then(result => result ? cell.getData().buchungsnr : Promise.reject({handled:true}))
+							.then(this.$fhcApi.factory.stv.konto.delete)
+							.then(() => {
+								// TODO(chris): deleting a child also removes the siblings!
+								//cell.getRow().delete();
+								this.reload();
+							})
+							.catch(this.$fhcAlert.handleSystemError);
+					});
+					container.append(button);
+
 					return container;
 				},
 				frozen: true
@@ -182,10 +201,24 @@ export default {
 		updateData(data) {
 			if (!data)
 				return this.reload();
-			this.$refs.table.tabulator.updateData(data);
+			// TODO(chris): check children (!delete?, multiple children)
+			//this.$refs.table.tabulator.updateOrAddData(data.map(row => row.buchungsnr_verweis ? {buchungsnr:row.buchungsnr_verweis, _children:row} : row));
+			this.$refs.table.tabulator.updateOrAddData(data);
 		},
 		actionNew() {
 			this.$refs.new.open();
+		},
+		actionCounter(selected) {
+			this.$fhcApi
+				.factory.stv.konto.counter({
+					buchungsnr: selected.map(e => e.buchungsnr),
+					buchungsdatum: this.counterdate
+				})
+				.then(result => result.data)
+				.then(this.updateData)
+				.then(() => 'Daten wurden gespeichert')
+				.then(this.$fhcAlert.alertSuccess)
+				.catch(this.$fhcAlert.handleSystemError);
 		}
 	},
 	created() {
@@ -221,11 +254,35 @@ export default {
 			table-only
 			:side-menu="false"
 			:tabulator-options="tabulatorOptions"
+			reload
 			new-btn-show
 			new-btn-label="Buchung"
 			:new-btn-disabled="stg_kz === ''"
 			@click:new="actionNew"
 			>
+			<template #actions="{selected}">
+				<div class="input-group w-auto">
+					<form-input
+						type="DatePicker"
+						v-model="counterdate"
+						input-group
+						:enable-time-picker="false"
+						auto-apply
+						@cleared="counterdate = new Date()"
+						>
+					</form-input>
+					<button
+						class="btn btn-outline-secondary"
+						@click="actionCounter(selected)"
+						:disabled="!selected.length"
+						>
+						Gegenbuchen
+					</button>
+				</div>
+				<button v-if="config.showZahlungsbestaetigung" class="btn btn-outline-secondary" @click="actionDownloadPdfs">
+					<i class="fa fa-download"></i> Zahlungsbestaetigung
+				</button>
+			</template>
 		</core-filter-cmpt>
 		<konto-new ref="new" :config="config" @saved="updateData" :person-ids="personIds" :stg-kz="stg_kz"></konto-new>
 		<konto-edit ref="edit" :config="config" @saved="updateData"></konto-edit>
diff --git a/system/phrasesupdate.php b/system/phrasesupdate.php
index abeb972a5..f4dd30a21 100644
--- a/system/phrasesupdate.php
+++ b/system/phrasesupdate.php
@@ -26573,6 +26573,26 @@ array(
 			)
 		)
 	),
+	array(
+		'app' => 'core',
+		'category' => 'sap',
+		'phrase' => 'msg_buchung_deleted',
+		'insertvon' => 'system',
+		'phrases' => array(
+			array(
+				'sprache' => 'German',
+				'text' => 'Buchungszuordnung SAP geloescht: SalesOrder: {sap_sales_order_id}',
+				'description' => '',
+				'insertvon' => 'system'
+			),
+			array(
+				'sprache' => 'English',
+				'text' => 'Buchungszuordnung SAP deleted: SalesOrder: {sap_sales_order_id}',
+				'description' => '',
+				'insertvon' => 'system'
+			)
+		)
+	),
 );