Does my wife need to self assess to declare US interest income ?

Briefly, since the UK taxes individuals and there is no provision for married filing joint we plan to split our US interest income on joint accounts 50/50.
On my self-assessment I will declare my half of the interest income.

But my wife has not worked in the UK and her total interest income from UK and US accounts is far below the standard personal allowance of £10,600.

So I wonder if she has to go ahead and self-assess, or can simply do nothing because of her total income being below £10,600.

Thanks in advance for any advice.

You are correct that she does not need complete a self assessment return. You can check the requirements explained here: https://www.gov.uk/self-assessment-tax-returns/who-must-send-a-tax-return