Tax calculation on new business startup and extra zero hours contract

Hello, I plan to open new business, however until it will fully grow, I plan to work somewhere on zero hours contract two days a week. How would I have to calculate payable tax on business assuming the company I would occasionally work for would pay my tax for me on the income I get there? Also, would the company pay emergency tax for my zero hours as I started a business?

Hi Aoshi,
You will need to submit a tax return to show the self employment and any other taxable income you receive.
This will then determine any tax due to be paid. the company you work for will not use an emergancy code once the new tax year starts, assuming you are employed before 05/04/24.
Please see this guidance:
Tax codes
Thank you.