Once you have filed a VAT return, you will not be able to edit the transactions in that period.
If there are any adjustments or if you wish to add any additional transactions, you can add it while generating the VAT returns for the subsequent periods.
When generating the new VAT return, check the option for ‘Include previous period’s unfiled transactions’ . This will include all older unfiled transactions that were added after filing the previous return.
Books
Online accounting software
for small businesses.