Form 29b: mat and its applicability

Sec 139D read with Rule 12 of Income Tax Rules, 1962 provides that 

The return of income required to be furnished in Form SAHAJ (ITR-1) or Form No. ITR-2 or Form No. ITR-3 or Form SUGAM (ITR-4S) or Form No. ITR-4 or Form No. ITR-5 or Form No. ITR-6 shall not be accompanied by a statement showing the computation of the tax payable on the basis of the return, or proof of the tax, if any, claimed to have been deducted or collected at source or the advance tax or tax on self-assessment, if any, claimed to have been paid or any document or copy of any account or form or report of audit required to be attached with the return of income under any of the provisions of the Act.

Sec 139D read with Rule 12 of Income Tax Rules, 1962 provides that 

The return of income required to be furnished in Form SAHAJ (ITR-1) or Form No. ITR-2 or Form No. ITR-3 or Form SUGAM (ITR-4S) or Form No. ITR-4 or Form No. ITR-5 or Form No. ITR-6 shall not be accompanied by a statement showing the computation of the tax payable on the basis of the return, or proof of the tax, if any, claimed to have been deducted or collected at source or the advance tax or tax on self-assessment, if any, claimed to have been paid or any document or copy of any account or form or report of audit required to be attached with the return of income under any of the provisions of the Act.

So does this mean that Form 29b does not have to filed anywhere? It just has to be kept on record?

Yes, ir has to be kept on record and has to be produced as and when Assessing Officer demands.