I want my children to start IRAs. They did some hourly work at church, and at year end received 1099s. Is there a maximum they can contribute, outside of the regular “below age 50” amounts ?

[Notlitnez2000]

Total income under $500.

[macuser_22]

If more than $400 of self-employed income then they must file a tax return and pay the SE tax on any amount over $400.

The most you can contribute to all of your traditional and Roth IRAs is the smaller of:

For 2019, $6,000, or $7,000 if you’re age 50 or older by the end of the year; or
your taxable compensation for the year.

(Taxable compensation is generally wages that you worked for - W-2 or net self-employed income minus the deducible part of the SE tax, but can include commissions, certain alimony and separate maintenance, and nontaxable combat pay ).

See IRS Pub 590A "What is compensation" for details:
https://www.irs.gov/publications/p590a#en_US_2018_publink1000230355

See this IRS article for Roth contribution limits:
https://www.irs.gov/retirement-plans/roth-iras

[dmertz]

Even if the compensation is less than the amount that requires filing Schedule SE and paying self-employment taxes, they are still required to report this income and, to support an IRA contribution it needs to be reported on Schedule C as income from self-employment.  The amount that will support an IRA contribution is the net profit shown on Schedule C minus the deductible portion of self-employment taxes, if any.

[Opus 17]

Because your children need to include a schedule C for their self-employment income and IRA contribution, you will need to upgrade to at least Turbotax Deluxe and pay probably over $100 per tax return if filing online.

You will want to prepare their returns using the IRS FreeFile version of Turbotax.  This is truly free for taxpayers with less than $36K of income and includes complicated forms that are not included in the regular "free" online version.  It's a separate web site from the regular online program. 

You will need to make a separate account with different user name and password for each tax return you need to file (they can be linked to the same email address).

https://freefile.intuit.com