Most Union army soldiers or their widows or minor children later applied for a pension. In some cases, a dependent father or mother applied for a pension. The pension files are indexed by NARA microfilm publication T288, General Index to Pension Files, 1861-1934 (544 rolls) and are available by request through NATF Form 80.

The pension file will often contain more information about what the soldier did during the war than the Compiled Service Record, and it may contain much medical information if he lived for a number of years afterwards.

To obtain a widow's pension, the widow had to provide proof of marriage, such as a copy of the record kept by county officials, or by affidavit from the minister or some other person. Applications on behalf of the soldier's minor children had to supply both proof of the soldier's marriage and proof of the children's birth.