Couples earning up to $1 million and more would be eligible for child tax credits of $1,650 per child in the Senate tax bill released Thursday evening. For individuals, the cut-off would be $500,000.

The bill, the Tax Cuts and Jobs Act, would set far more generous parameters for the benefit than exist today. Under current law, eligibility for the credit begins to phase out at $110,000 for couples and $75,000 for individuals.

Under the House version of the tax legislation, the child tax credit would begin to phase out at $230,000 for couples and $115,000 for individuals.

In other words, Senate Republicans aim to make the tax credits available much further up the income spectrum, allowing even rich families to claim them.

The Senate bill would also make the refundable portion of the credit available to more low-income earners, and index it to inflation. It would keep the value at the present $1,000, though. A refundable credit is available to taxpayers who don't have income tax liability, meaning that the government essentially cuts them a check.

Also, it doesn't include a $300 family credit included in the House bill.

The size and structure of the child tax credit is a key consideration in the upper chamber. Already Thursday, two Republicans — Marco Rubio of Florida and Mike Lee of Utah -- said that they were not big enough.

Altogether, the Senate expansion of the credits would amount to a $582 billion tax cut over 10 years.

The bill, however, would claw back some of those cuts by requiring families to provide Social Security numbers to claim the refundable part of the credit, saving $24 billion.