Tax codes are different from tax rates.
Tax codes only apply to individuals. They help your employer or payer work out how much tax to deduct before they pay you.
You use tax rates to work out how much tax you need to pay on your total income for the year, from all sources.
Individuals pay progressive tax rates. This means you pay a graduated amount, depending on how much income you get.
Businesses pay a fixed rate, depending on the type of business.