Amendment in Returns:
Return of Service Tax or / and Return of CENVAT credit can be revised whenever required in Form ST-3
Service Tax return can be revised - within 90 days from the date of filing of the original return.
CENVAT credit return can be revised - within 60 days from the date of filing of the original return.
In case of E filing, it can be revised only once.
(Rule 7B, Service Tax Rules, 1994; Rule 9(11), CENVAT Credit Rules, 2004)