查到细节了, 只有5年, 收入23万以上开始phase out.

Expands child tax credit: The bill would increase the child tax credit to $1,600, up from $1,000, for any child under 17.

But that $600 increase won't be available to the lowest-income families if they don't end up owing federal income taxes. That's because unlike the first $1,000, the extra $600 won't be refundable. Refundable means that if your federal income tax bill is zero, you get a check from the government because of the credit.

The bill would let more people claim the child tax credit. The income level where the credit starts to be phased out would increase to $115,000 for single parents, up from $75,000 today, and to $230,000 for married parents, up from $110,000.

Creates two new family credits: The bill would create two different $300 tax credits, but they would be in effect only for five years and would not be refundable.

The first would be for nonchild dependents -- for instance, any son or daughter over 17 whom you're supporting, an ailing elderly mother or an adult child with a disability. The second is a credit for each spouse if they file jointly (or, in the case of single parents, the head of household).

So a family of four -- two parents, a 12-year-old daughter and an 18-year-old son -- could reduce their tax bill by $2,500, said Elaine Maag, a senior research associate at the Urban Institute. They would claim the $1,600 child tax credit for the daughter, the $300 nonchild dependent credit for the son and a $300 credit for each parent.

The income thresholds governing these two new credits are the same as for the child tax credit.