Hi Vipasha,

2.Class XII Provisional/ Original Certificate/ Mark Sheet

3.Recent Character Certificate

4.Transfer/ Migration Certificate

5.Recent Passport Size Photograph

6.Scanned Signature

7.PWD/ ST/ SC certificate (Only for the candidates belonging to these categories)

8.OBC - NCL (Non-Creamy Layer) Certificate (if applicable)
9.Income Certificate (OBC-NCL)

10.Kashmir Migrant Certificate (Only those applying under Kashmir Migrant Quota)

11.Educational Concession Certificate (Only CW Quota)

12.ECA Distinction/ Sports Certificate (last three years – April 1, 2016, to March 31, 2019)

So, yes income certificate is an important part of the documents required by Delhi University  to complete the application process.
All the best! :)