Self-assessment is forcing me to declare my income as foreign, and then skipping NIC taxes

I'm a web developer and I work almost exclusively through Upwork, a freelancer platform based in the US. Up until now when doing self-assessment, I would declare this as normal income and pay standard income tax and NIC's on it, skipping the "Foreign income" section (I received advice a while ago to do it this way). Starting this year, it's forcing me to tick the "Foreign income" box and to complete this section, saying it has received information from outside agencies that I receive foreign income. So I enter my UK work into the standard income section (~£5k) and then my Upwork income as ~£30k in Foreign Income as "All other income received by a person abroad and any remitted 'ring fenced' foreign income". Now I notice that the final calculation of my tax for the year is £3k less, appearing to skip NIC's and only charging me for income tax and my student loan. Is this correct?

Hi,

The foreign income also needs to be declared as self employed income in order for it to be included in your calculation. When declaring at as foreign income at the employment or self employment page it doesnt add it.

Thank you.