Can anyone explain the 2 child rule affecting tax credits from April 2017. I understand that if you already claim TC and have a 3rd child then you won't get extra tax credits for the 3rd child. However if I don't currently claim any TC but my circumstances change and I am eligible to claim them after April 2017 ( so would be a new claim) can I claim for all 3 of my kids under 18 or only 2 of them? Thankyou for any clarification.