Question:
Why is there no Bismilla in the beginning of surah taubah?
 
Answer: 
There are 114 chapters in the holy Quraan and all of them have Bismilla in the beginning except chapter 9. Sayyidina Ali RA used to say that Bismilla is symbolic of Almighty Allahs mercy and the subject matter of surah taubah primarily comprises punishment of the hypocrites and disbelievers etc. Hence the Bismilla has been omitted.