The Federal Tax Administration (FTA) has published a circular on printed matters (order forms) concerning direct federal tax, the flat-rate tax credit (pStA) and the additional tax retention USA (zStR USA) for the 2019 tax period for the attention of the cantonal administrations for direct federal tax and the central withholding tax authorities of the cantons.
The circular 2-171-DV-2019-d of 29 March 2019 with further details is available here.
All FTA circulars are available here.