FB1S Missing clearing information in table BSEG

IF you need to have the field AUFNR in the clearing line item, you have the option to work with a clearing rule.
1) Go to transaction OBIA and define a clearing rule.
2) Assign the field AUFNR to the clearing rule.
3) Save the definitions.
4) Go to transaction OBIB and assign the clearingrule to the concerned account type.
5) Save the changes.

Please see note 543898.