Usually, the due date to submit a VAT return is the end of the second month following the reporting period. For the exact filing deadlines, please check this article. In December the VAT filing procedure in Italy differs from the other months.

Please read here the procedure for the December VAT return filing in Italy:

• Based on the sales numbers of the previous year, the VAT amount for the months of December is being calculated.
• Before the year ends, you pay the calculated VAT amount to the Italian Tax Authorities.
• In January, the actual VAT amount for the month of December is calculated.
• The difference between the actual VAT amount and the previously paid amount will be either used for future payments or you will be asked to pay the difference.

Example:

•  In December 2021 the amount of 10.000 EU has been paid to the Italian Tax authorities. This amount is being taken as the pre-payment amount for December 2022. 

• In January 2023, the actual VAT amount of 11.000 EU is being calculated. The pre-paid amount of 10.000 EU is being deducted and 1.000 EU is being left to be paid.