VAT Redetermine - userexit

Does anyone know which userexit can we use in redetermination of VAT.

The requirement inside the userexit:

If vbtyp = 'O' AND (credit note posting date - billing date) > 365 days, it will redetermine the vat. the value of MWST should be changed and pricing type will be equal to 'G'.

the value of amount should not be '0,000'.