Challan Number is a 5 digit Challan Serial Number mentioned by the receiving bank. It automatically gets generated by the bank once payment is done by Payer/ Deductor. 

It is not possible to add challan details without Challan Number while filing e-TDS Return. In case there is no challan number mentioned in challan given by the bank then one needs to contact the bank. 

Read More: How to deposit Tax Deducted (TDS) online?