Levi Johnston Child Support Verdict: Johnston Must Pay $1,750 Per Month To Bristol Palin

05/16/2010 05:12 am ET | Updated May 25, 2011

ANCHORAGE, Alaska — The teen father of Sarah Palin's grandson has been ordered to make interim child support payments of $1,750 per month to Palin's daughter.

The amount is 20 percent of 19-year-old Levi Johnston's adjusted annual income as set out in Alaska statute.

Bristol Palin, also 19, is the oldest daughter of former Alaska Gov. Sarah Palin, the GOP vice presidential nominee in 2008.

Tripp, the son of Bristol Palin and Johnston, was born in December 2008.

Johnston's payments are based on estimated income of $105,000 and are retroactive to May 2009. The payments are slightly lower for January through April 2009 because of Johnston's lower income.

Palmer Superior Court Judge Judge Kari C. Kristiansen set a trial date in the matter for Sept. 23.