Form type markup states
Adding form type item did the trick:
$form['my_incomes'] = [
      '#type' =&gt; 'item',
      '#markup' =&gt; $this-&gt;t('My other incomes'),
      '#states' =&gt; [
        'visible' =&gt; [
          [':input[name=&quot;marital_status&quot;]' =&gt; [['value' =&gt; 'single'],['value'=&gt;'couple']]],
        ]
      ]
    ];