Oh dear Gertrude, you're SO predictable!
The quickest Google in the world yields (among others)
Jalia Linux Accounting -
http://jalia.sourceforge.net/
"5. Financials – V.A.T :
The financials module provides you with VAT features. All your transactions recorded in the Jalia application automatically update the VAT related information. Using VAT, you can draw out your VAT Liability for a given period and arrange for payment/receipts to/from the statutory authority. Once you make or receive a payment, those transactions can be flagged off as having being reconciled thus avoiding future duplicity."
Also the Kalculate Financial Accounting Package for Linux -
http://www.kalculate.com/ - "VAT ready"
Banana Accounting -
http://www.banana.ch/base/eng/welcome.shtml supports VAT
I'm too bored to go on.