Why do UC need last 12 months earnings??

[RapidRainbow]

Helping a family member claim UC after losing their job. Partner still self employed but no income at moment.

What good will previous earnings be to UC? How does it impact a new claim? Seems a pointless exercise!

Possibly to assess if they are eligible for any other benefits? Eg if they are entitled to New Style JSA (based on NI contributions) then that reduces their UC £-£.

Might be to do with this www.citizensadvice.org.uk/benefits/universal-credit/on-universal-credit/how-the-minimum-income-floor-works-if-youre-self-employed/

To assess if you are eligible to certain benefits or a grace period for claiming certain things ie childcare or eligible for relief against benefit cap or to get an advance