Partnership (Short) Form SA 104S

My wife and I are Non-Resident Landlords with a rented property in the UK (registered in both our names as equal owners) - we each submitted a Self-Assessment Tax Return for 2023 - splitting the rental income and expenses 50/50 and completing the Married Couple's allowance. Now HMRC have rejected her return asking for completion of a Partnership Form SA 104S. This asks for a Partnership Reference Number. What is this? Where does one get this number from? Why does she and not me need to complete this form?

Hi Ian Bloxam,
If you have shown the income as partnership income rather than rental income on the tax return then there should be an actual partnership that shows the total income received.
It may be a case of therefore resubmtting the form with the SA105 income from property page.
As non resident, you also need the SA109 residence page.
Thank you.