deficit in stamp duty. As the document was not registered though required as per Section 17 of the Registration Act, it is inadmissible in evidence by virtue of Section 49 of the Registration Act. However, Section 49 itself carved out exceptions to the general principle of inadmissibility of a document in evidence for want of registration. Therefore, a document though requires registration, when not registered, can be received in evidence for the proof of collateral transaction which does not require registration. Here, the contention is that the document is relied on for the main purpose of establishing one of the terms of contract of lease regarding the rate of rent. Therefore, it cannot be said as a collateral transaction which can be established through the said unregistered document. When the said document is sought to be used in evidence for the purpose of establishing the rate of rent, as it is not a collateral transaction, the said document cannot be received in evidence. Of course, since the objection on the ground of want of registration can be decided not only at the time of raising objection, but also even at a later stage, in the present case, it may not be the only ground to de-exhibit document already marked as exhibit A6. Even when an unregistered document is received for collateral transaction, it must be indicted or else, it may be used for main transaction also. But,