public Table LineFeatureTable {get;}

string errorMessage = await QueuedTask.Run(() =>
{
  try
  {
    var myParcelFabricLayer = MapView.Active.Map.GetLayersAsFlattenedList().OfType<ParcelLayer>().FirstOrDefault();
    //if there is no fabric in the map then bail
    if (myParcelFabricLayer == null)
      return "There is no fabric in the map.";
    string myParcelTypeName = "Tax";
    var myParcelFabricDataset = myParcelFabricLayer.GetParcelFabric();
    var typeInfo = myParcelFabricDataset.GetParcelTypeInfo();
    FeatureClass lineFCType = null;
    FeatureClass polyFCType = null;
    foreach (var info in typeInfo)
    {
      if (info.Name.ToLower() == myParcelTypeName.ToLower())
      {
        lineFCType = info.LineFeatureTable as FeatureClass;
        polyFCType = info.PolygonFeatureTable as FeatureClass;
        break;
      }
    }
  }
  catch (Exception ex)
  {
    return ex.Message;
  }
  return "";
});
if (!string.IsNullOrEmpty(errorMessage))
  MessageBox.Show(errorMessage, "Get Parcel Type feature classes.");