On Ancestry.com I found Thomas Scott with an Aug. 25, 1863 date. He is in the Civil War Draft Registration Records. He was a married wagon maker in Peoria; born about 1832 in Pennsylvania.
Draft registration does not mean he actually served.
I looked at Thomas Scotts in Iowa regiments but no match. He was living in Taylor, Benton County, Iowa in 1856 and Center, O'Brien County, Iowa in 1885.