There's a little more to it than that, though I agree that opt in would be better. For 2021 only, the ctc is increased to 3000 per spawn, 3600 for under 6 (I think), so there's an increased credit that these monthly payments are working against. But... The monthly payments will exceed the extra 1k credit by 500, so refunds will go down by that much. Like you, I carefully plan my taxes and will be increasing my w2 withholding by 200 per month (2 spawn here) to compensate. Luckily, for fed gov employees, that's super easy.