Child Maintenance - untaxed overseas income?

[ZippedyZipZip]

Niche question so new username!

Im trying to do my figures. I can do the child maintenance service calculator based on taxable income. But he also receives an non taxable payment from overseas of around £1,000 per month (military disability payments, non taxable by way of treaty between the countries, this is not under the radar stuff). Does anyone know whether this would be treated as income for child maintenance purposes?

From what i understand not in the initial calculation.
But you then apply for a variation that takes in account other sources of income, (interest on savings, rental income ect) it may be applicable there.

That’s really helpful, thank you!