As per the UGC latest guideline, a student can do two courses simultaneously provided one of the course is to be done through Distance Mode. So yeah! You can obviously do your Diploma in Taxation through Distance mode along with your BCOM and there are no problem, your both courses will be accounted valid.

To know more about Diploma in Taxation Law, visit the link below:

https://www.careers360.com/courses/diploma-in-taxation-law

I hope this answer helps. All the very best for your future endeavors!