Dividend tax reduction without dividend income

My tax coding notice shows a reduction of dividend tax in the calculation of my tax code. However, I don't receive any dividends. How do I find out what this reduction refers to/where it comes from?

Hi Ed Garey,

If you aren't receiving any dividends contact our helpline and we can review the tax code.
Income Tax: general enquiries

Thank you.

Thanks. It looks like the helpline isn't actually open at the moment, unless there's another one I can access? https://www.gov.uk/government/organisations/hm-revenue-customs/contact/self-assessment

Hi,

The helpline has reopened as of 04 September 2023.

Thank you.