Does it make a difference if I divide ink cartridge expenses among my businesses, or just list them all under one of them?

[DianeW · Accepted solution]

Your expenses should be reflected against the income in proportion to the business activity of each business.  This can be a simple formula of income received from each business as a percentage to the total income received from all businesses.  This same formula would apply to any expenses that are attributable to all business activities you operate.