I’m not sure how but you definitely should be able to as mine comes through 4 weekly which is basically monthly 😊
Ring them up and ask for it to be a 4 weekly payment :)
Maybe on HMRC app ?
Child benefit helpline & ask to change to monthly payment 0300 200 3100
I’m not sure how but you definitely should be able to as mine comes through 4 weekly which is basically monthly 😊