I have an LLC set up, and am learning my way with regards to keeping books etc. I was told recently that I can use the business bank account to pay up to 50% of my rent (being that I am the owner, and it's a place of operating for the business), and write it off as a business expense. Is this true, and how should I go about doing so? Any help would be great!
The majority of the time it's not worth it to even go anywhere near this.
Rather than pay 1/2 your rent, and potentially have to deal with more complex tax filings, attracting audit attention, potential issues with your landlord (many renters contracts have clauses about the property not being used for business, etc.) you should just have the business pay you some amount of money that you can use to help cover rent. Yes, you'll lose out some on taxes, but you'll make up for it multiple times over, IME, with reduced accounting hassles.
My accountant has advised me not go anywhere near the home office deduction. According to him, it is akin to hanging a "Please Audit Me Sign" on your door and is not worth the limited benefits.
That's just one accountant's opinion - I would check with yours.
You should should ask your accountant (if you don't have one, get one - they usually save you more than you pay them).
That being said, in the UK (I know you're in CA but this might help others with your question) you can claim up to half your mortgage/rent as a business expense but you need to register your property as being residential and commercial with the council (which can cause issues). There is also a qualifying criteria you need to meet.