Due date for filing IT return!

even if it is nt having the tax liability still trust is req ti file the return if its gross income exceeds the exemption limit......though after the deduction its income goes below the exemption limit....

well, I know that trust is compulsorily required to file return in the above situation but my query is whether the return should be mandatorily filed within 30th september? If there is no tax liablity, cant it be filed afterwards?

Sourav