Families across the United States could be getting a large check from the government starting this week.

The reason? A federal law passed in March regarding child tax credits.

The IRS estimates about 39 million families will be getting an increase in what is called a child tax credit.

These families will be getting checks from the government that amount to nearly double what they may have been eligible for before.

Before this law passed in March, the maximum a family could receive per child was $2,000 for the year.

Now, for each child under 6, people get $3,600 for the year. According to one financial advisor, the IRS bases a child's age on how old they turn at the end of the year. That means if you child turns 6 in 2021, the maximum you can get is $3,000 opposed to $3,600.

For each kid between 6 and 17, it's $3,000. Eighteen year olds are not eligible.

The way you get these maximum amounts your joint household income has to be at most $150,000.

There are also thresholds if you file as a head of household or a single filer, too.

If you make more, the amount you get from the government drops.

So how do you get the child tax credit?

Most parents don't have to do anything if they filed taxes in 2019 and 2020.

They will automatically get this money if they are eligible.

These families do have a decision to make.

By default, the government is going to send a check every month for six months.

For example, if you are eligible for $3,600, you'll get half in monthly checks. So, $300 a month until the end of the year - and then get the rest when filing your 2021 taxes.

People can accept the monthly payments or can opt out and get one check when they file their taxes.

"For many people this is going to be an important supplement they can use now. For others who may not feel a need now, I'm used to claiming it every year on my tax return. I'll just continue to do the same," says Paul Herman, of Herman & Company CPA'S.

When it comes to couples who are divorced, the tax credit should go to the parent who claims their child or children as dependents, according to Joseph Zaino, who is a partner at Revonary Accountants and Advisors in Rye Brook.

Tax professionals News 12 have consulted with have a warning - if your income dramatically dropped last year during the pandemic and then went back up this year, you may want to opt out. This is because if your income is too high for the child tax credit, that will be reflected in your 2021 taxes, and when you file, you could owe the government thousands of dollars.

If you are looking for a way to opt out of the monthly child tax credit payments, click on this link.