Field help (VATFRMOFF) 

Select this checkbox to run the VAT calculations in offline mode.

An offline form or declaration cannot be switched to an online form or declaration if anything is linked to the form such as a VAT return. Running an actual extraction in offline mode updates the declared VAT at the journal entry level.

You can have an active, online version for the same declaration and legislation.

For UK declarations: Online submission to HMRC for British VAT is not possible with an offline form.