The submission deadlines for the advance VAT return and the wage tax return are set by law. You must submit the tax return to the tax office within the respective deadline and (in the case of a payment charge) pay the tax you have calculated to the tax office.
In case of late submission of the tax return, the tax office may impose a late payment surcharge (§ 152 AO). Please also note that late payment penalties may be incurred if you do not pay the tax on time by the due date.