diff --git a/application/controllers/codex/UHSTAT1.php b/application/controllers/codex/UHSTAT1.php
index 4486f9d74..38b0f3b6d 100644
--- a/application/controllers/codex/UHSTAT1.php
+++ b/application/controllers/codex/UHSTAT1.php
@@ -363,7 +363,11 @@ class UHSTAT1 extends FHC_Controller
 
 		// get realistic birth years, dated back from current year
 		$currYear = date("Y");
-		$formMetaData['jahre'] = range($currYear - self::UPPER_BOUNDARY_YEARS, $currYear - self::LOWER_BOUNDARY_YEARS);
+		$yearRange = range($currYear - self::UPPER_BOUNDARY_YEARS, $currYear - self::LOWER_BOUNDARY_YEARS);
+		$formMetaData['jahre'] = array_combine($yearRange, $yearRange);
+
+		// add "unknown" option
+		$formMetaData['jahre'][9999] = 'unbekannt';
 
 		return success($formMetaData);
 	}
diff --git a/application/views/codex/uhstat1.php b/application/views/codex/uhstat1.php
index 78a30b3e5..a255781f1 100644
--- a/application/views/codex/uhstat1.php
+++ b/application/views/codex/uhstat1.php
@@ -74,16 +74,23 @@ $saved = isset($saved) && $saved === true;
 				<div class="form-group">
 					<label for="mutter_geburtsjahr" class="col-sm-3 control-label"><?php echo ucfirst($this->p->t('uhstat', 'geburtsjahr')) ?></label>
 					<div class="col-sm-9">
-						<select type="text" name="mutter_geburtsjahr" id="mutter_geburtsjahr" class="form-control" <?php echo $disabled ?>>
-							<option disabled selected value=""><?php echo $this->p->t('uhstat', 'bitteAuswaehlen') ?></option>
-							<?php foreach ($formMetaData['jahre'] as $jahr): ?>
-								<option
-									value="<?php echo $jahr ?>"
-									<?php echo $jahr == $mutter_geburtsjahr ? " selected" : "" ?>>
-									<?php echo $jahr ?>
-								</option>
-							<?php endforeach; ?>
-						</select>
+						<div class="input-group">
+							<select type="text" name="mutter_geburtsjahr" id="mutter_geburtsjahr" class="form-control" <?php echo $disabled ?>>
+								<option disabled selected value=""><?php echo $this->p->t('uhstat', 'bitteAuswaehlen') ?></option>
+								<?php foreach ($formMetaData['jahre'] as $jahrKey => $jahr): ?>
+									<option
+										value="<?php echo $jahrKey ?>"
+										<?php echo $jahrKey == $mutter_geburtsjahr ? " selected" : "" ?>>
+										<?php echo $jahr ?>
+									</option>
+								<?php endforeach; ?>
+							</select>
+							<span class="input-group-btn">
+								<button type="button" class="btn btn-default" onclick="document.getElementById('mutter_geburtsjahr').value = 9999; return false;" <?php echo $disabled ?>>
+									<?php echo $this->p->t('uhstat', 'unbekannt') ?>
+								</button>
+							</span>
+						</div>
 						<?php echo form_error('mutter_geburtsjahr'); ?>
 					</div>
 				</div>
@@ -94,16 +101,23 @@ $saved = isset($saved) && $saved === true;
 						<?php echo '('.ucfirst($this->p->t('uhstat', 'inDenHeutigenGrenzen')).')' ?>
 					</label>
 					<div class="col-sm-9">
-						<select type="text" name="mutter_geburtsstaat" id="mutter_geburtsstaat" class="form-control" <?php echo $disabled ?>>
-							<option disabled selected value=""><?php echo $this->p->t('uhstat', 'bitteAuswaehlen') ?></option>
-							<?php foreach ($formMetaData['nation'] as $nation): ?>
-								<option
-									value="<?php echo $nation->nation_code ?>"
-									<?php echo $mutter_geburtsstaat == $nation->nation_code ? " selected" : "" ?>>
-									<?php echo $nation->nation_text ?>
-								</option>
-							<?php endforeach; ?>
-						</select>
+						<div class="input-group">
+							<select type="text" name="mutter_geburtsstaat" id="mutter_geburtsstaat" class="form-control" <?php echo $disabled ?>>
+								<option disabled selected value=""><?php echo $this->p->t('uhstat', 'bitteAuswaehlen') ?></option>
+								<?php foreach ($formMetaData['nation'] as $nation): ?>
+									<option
+										value="<?php echo $nation->nation_code ?>"
+										<?php echo $mutter_geburtsstaat == $nation->nation_code ? " selected" : "" ?>>
+										<?php echo $nation->nation_text ?>
+									</option>
+								<?php endforeach; ?>
+							</select>
+							<span class="input-group-btn">
+								<button type="button" class="btn btn-default" onclick="document.getElementById('mutter_geburtsstaat').value = 'XXX'; return false;" <?php echo $disabled ?>>
+									<?php echo $this->p->t('uhstat', 'unbekannt') ?>
+								</button>
+							</span>
+						</div>
 						<?php echo form_error('mutter_geburtsstaat'); ?>
 					</div>
 				</div>
@@ -114,16 +128,23 @@ $saved = isset($saved) && $saved === true;
 						<?php echo '('.ucfirst($this->p->t('uhstat', 'inDenHeutigenGrenzen')).')' ?>
 					</label>
 					<div class="col-sm-9">
-						<select type="text" name="mutter_bildungsstaat" id="mutter_bildungsstaat" class="form-control" <?php echo $disabled ?>>
-							<option disabled selected value=""><?php echo $this->p->t('uhstat', 'bitteAuswaehlen') ?></option>
-							<?php foreach ($formMetaData['nation'] as $nation): ?>
-								<option
-									value="<?php echo $nation->nation_code ?>"
-									<?php echo $mutter_bildungsstaat == $nation->nation_code ? " selected" : "" ?>>
-									<?php echo $nation->nation_text ?>
-								</option>
-							<?php endforeach; ?>
-						</select>
+						<div class="input-group">
+							<select type="text" name="mutter_bildungsstaat" id="mutter_bildungsstaat" class="form-control" <?php echo $disabled ?>>
+								<option disabled selected value=""><?php echo $this->p->t('uhstat', 'bitteAuswaehlen') ?></option>
+								<?php foreach ($formMetaData['nation'] as $nation): ?>
+									<option
+										value="<?php echo $nation->nation_code ?>"
+										<?php echo $mutter_bildungsstaat == $nation->nation_code ? " selected" : "" ?>>
+										<?php echo $nation->nation_text ?>
+									</option>
+								<?php endforeach; ?>
+							</select>
+							<span class="input-group-btn">
+								<button type="button" class="btn btn-default" onclick="document.getElementById('mutter_bildungsstaat').value = 'XXX'; return false;" <?php echo $disabled ?>>
+									<?php echo $this->p->t('uhstat', 'unbekannt') ?>
+								</button>
+							</span>
+						</div>
 						<?php echo form_error('mutter_bildungsstaat'); ?>
 					</div>
 				</div>
@@ -161,16 +182,23 @@ $saved = isset($saved) && $saved === true;
 				<div class="form-group">
 					<label for="vater_geburtsjahr" class="col-sm-3 control-label"><?php echo ucfirst($this->p->t('uhstat', 'geburtsjahr')) ?></label>
 					<div class="col-sm-9">
-						<select type="text" name="vater_geburtsjahr" id="vater_geburtsjahr" class="form-control" <?php echo $disabled ?>>
-							<option disabled selected value=""><?php echo $this->p->t('uhstat', 'bitteAuswaehlen') ?></option>
-							<?php foreach ($formMetaData['jahre'] as $jahr): ?>
-								<option
-									value="<?php echo $jahr ?>"
-									<?php echo $vater_geburtsjahr == $jahr ? " selected" : "" ?>>
+						<div class="input-group">
+							<select type="text" name="vater_geburtsjahr" id="vater_geburtsjahr" class="form-control" <?php echo $disabled ?>>
+								<option disabled selected value=""><?php echo $this->p->t('uhstat', 'bitteAuswaehlen') ?></option>
+								<?php foreach ($formMetaData['jahre'] as $jahrKey => $jahr): ?>
+									<option
+										value="<?php echo $jahrKey ?>"
+										<?php echo $vater_geburtsjahr == $jahrKey ? " selected" : "" ?>>
 										<?php echo $jahr ?>
 									</option>
-							<?php endforeach; ?>
-						</select>
+								<?php endforeach; ?>
+							</select>
+							<span class="input-group-btn">
+								<button type="button" class="btn btn-default" onclick="document.getElementById('vater_geburtsjahr').value = 9999; return false;" <?php echo $disabled ?>>
+									<?php echo $this->p->t('uhstat', 'unbekannt') ?>
+								</button>
+							</span>
+						</div>
 						<?php echo form_error('vater_geburtsjahr'); ?>
 					</div>
 				</div>
@@ -181,16 +209,23 @@ $saved = isset($saved) && $saved === true;
 						<?php echo '('.ucfirst($this->p->t('uhstat', 'inDenHeutigenGrenzen')).')' ?>
 					</label>
 					<div class="col-sm-9">
-						<select type="text" name="vater_geburtsstaat" id="vater_geburtsstaat" class="form-control" <?php echo $disabled ?>>
-							<option disabled selected value=""><?php echo $this->p->t('uhstat', 'bitteAuswaehlen') ?></option>
-							<?php foreach ($formMetaData['nation'] as $nation): ?>
-								<option
-									value="<?php echo $nation->nation_code ?>"
-									<?php echo $vater_geburtsstaat == $nation->nation_code ? " selected" : "" ?>>
-										<?php echo $nation->nation_text ?>
-								</option>
-							<?php endforeach; ?>
-						</select>
+						<div class="input-group">
+							<select type="text" name="vater_geburtsstaat" id="vater_geburtsstaat" class="form-control" <?php echo $disabled ?>>
+								<option disabled selected value=""><?php echo $this->p->t('uhstat', 'bitteAuswaehlen') ?></option>
+								<?php foreach ($formMetaData['nation'] as $nation): ?>
+									<option
+										value="<?php echo $nation->nation_code ?>"
+										<?php echo $vater_geburtsstaat == $nation->nation_code ? " selected" : "" ?>>
+											<?php echo $nation->nation_text ?>
+									</option>
+								<?php endforeach; ?>
+							</select>
+							<span class="input-group-btn">
+								<button type="button" class="btn btn-default" onclick="document.getElementById('vater_geburtsstaat').value = 'XXX'; return false;" <?php echo $disabled ?>>
+									<?php echo $this->p->t('uhstat', 'unbekannt') ?>
+								</button>
+							</span>
+						</div>
 						<?php echo form_error('vater_geburtsstaat'); ?>
 					</div>
 				</div>
@@ -201,16 +236,23 @@ $saved = isset($saved) && $saved === true;
 						<?php echo '('.ucfirst($this->p->t('uhstat', 'inDenHeutigenGrenzen')).')' ?>
 					</label>
 					<div class="col-sm-9">
-						<select type="text" name="vater_bildungsstaat" id="vater_bildungsstaat" class="form-control" <?php echo $disabled ?>>
-							<option disabled selected value=""><?php echo $this->p->t('uhstat', 'bitteAuswaehlen') ?></option>
-							<?php foreach ($formMetaData['nation'] as $nation): ?>
-								<option
-									value="<?php echo $nation->nation_code ?>"
-									<?php echo $vater_bildungsstaat == $nation->nation_code ? " selected" : "" ?>>
-										<?php echo $nation->nation_text ?>
-								</option>
-							<?php endforeach; ?>
-						</select>
+						<div class="input-group">
+							<select type="text" name="vater_bildungsstaat" id="vater_bildungsstaat" class="form-control" <?php echo $disabled ?>>
+								<option disabled selected value=""><?php echo $this->p->t('uhstat', 'bitteAuswaehlen') ?></option>
+								<?php foreach ($formMetaData['nation'] as $nation): ?>
+									<option
+										value="<?php echo $nation->nation_code ?>"
+										<?php echo $vater_bildungsstaat == $nation->nation_code ? " selected" : "" ?>>
+											<?php echo $nation->nation_text ?>
+									</option>
+								<?php endforeach; ?>
+							</select>
+							<span class="input-group-btn">
+								<button type="button" class="btn btn-default" onclick="document.getElementById('vater_bildungsstaat').value = 'XXX'; return false;" <?php echo $disabled ?>>
+									<?php echo $this->p->t('uhstat', 'unbekannt') ?>
+								</button>
+							</span>
+						</div>
 						<?php echo form_error('vater_bildungsstaat'); ?>
 					</div>
 				</div>
@@ -271,7 +313,7 @@ $saved = isset($saved) && $saved === true;
 				</div>
 			</form>
 		<?php endif; ?>
-	</div>
-</div>
+	</div> <!-- subcontainer -->
+</div> <!-- container -->
 
 <?php $this->load->view('templates/FHC-Footer'); ?>
diff --git a/system/phrasesupdate.php b/system/phrasesupdate.php
index ad2b6aa57..6fcaf4bf6 100644
--- a/system/phrasesupdate.php
+++ b/system/phrasesupdate.php
@@ -24698,7 +24698,7 @@ array(
 				'insertvon' => 'system'
 			)
 		)
-	),	
+	),
 	array(
 		'app' => 'personalverwaltung',
 		'category' => 'gehaltsband',
@@ -26942,6 +26942,26 @@ array(
 		)
 	),
 	// Betriebsmittel end
+	array(
+		'app' => 'core',
+		'category' => 'uhstat',
+		'phrase' => 'unbekannt',
+		'insertvon' => 'system',
+		'phrases' => array(
+			array(
+				'sprache' => 'German',
+				'text' => 'unbekannt',
+				'description' => '',
+				'insertvon' => 'system'
+			),
+			array(
+				'sprache' => 'English',
+				'text' => 'unknown',
+				'description' => '',
+				'insertvon' => 'system'
+			)
+		)
+	)
 );