Field help (KAMTVATRCU) 

This field contains the recovered VAT amount in transaction currency. It is automatically calculated based on the invoiced VAT amount and the collection rate. The amount thus calculated can be modified by the user only if the collection rate is different from 0% and lower than 100%.
The entry of a recovered VAT amount equal to 0 is allowed. In that case, the rate is automatically set to 0.
If the expense originates from the validation of an invoice or validation/entry of an accounting document, this value is forced with the recovered VAT amount of the source document. It is recalculated in case one of the VAT coefficients or the activity sector are modified, thus defining a new recovered VAT rate.