24 May 2018
Not possible you can not fill PAN Or TAN Viceversa wrongly field restrictions not allow you PAN Contains 6 alphabets 4 numerics while TAN 5 and 5 alphabet. Any interchange not allow you to enter filed.
25 May 2018
Yes. As per Expert's reply we can not use PAN instead of TAN. ETDS return will not get validated. So check your ETDS return whether accepted at TRACES or not and file a correction / fresh return accordingly.