The SII information has to be submitted in a time frame of four calendar days, more precisely:
Book of Records
Within four calendar days after invoice issuance
Within four calendar days after the entry into the accounting system
Certain Intra-Community Transactions
Within the four calendar days of the date of dispatch or transport or, if applicable, from the date of receipt of the goods in question.
Within the filing period of the last settlement of the year (up to 30 January)
The term of four calendar days excludes Saturdays, Sundays and national holidays.