Field help (VATSAIVAT) 

This field contains the amount that has already been involved in the VAT declaration. Depending on the entry lines, this amount can be:

This amount is signed.

If you reset it to zero, the entry line will be included again in the declaration processing.

SEEWARNING These operations are to be performed with caution and must involve a homogeneous set of entry lines.Applying an inconsistent change to these declared amounts can alter the declaration results.