I have an itemized cell phone bill each month that I pay. I know what percentage I can claim as a business expense. I recently separated out my personal and business account and when my cell phone bill came up this month I paid it from my business account ( I realize that I could have split the payment between my business and personal account, but I didn't). I've recorded that expense in zoho books and matched it to withdrawal in my bank feed. My question is how or where do split the difference between what I can claim as a business expense and what is a personal expense so that the expense only reflect the percentage I can actually take.

Apologies if that was confusing it's just a situation I am not sure how to handle and it will likely come up for other expenses like gas and car maintenance.

Thanks for any help that could be provided.