LES Question

My mid month pay stub populated today on mypay. It is approximately 200$ less than I was expecting (I’m in the middle of a bump from my +2 years of service this month).

Approx 2 days ago I changed my allotment from 150$ a month to 500$ a month to my brokerage account. I didn’t think that changes on paychecks were that fast? Also the math doesn’t add up?

Anyone have a quick answer for me?

Side question, why do we not get full LESs for a mid month paycheck, kind of annoying when something is wrong.