<ACCESSION-NUMBER>0001437749-18-020224 <TYPE>10-Q <PUBLIC-DOCUMENT-COUNT>85 <PERIOD>20180930 <FILING-DATE>20181109 <DATE-OF-FILING-DATE-CHANGE>20181109 <FILER> <COMPANY-DATA> <CONFORMED-NAME>Otter Tail Corp <CIK>0001466593 <ASSIGNED-SIC>4911 <IRS-NUMBER>270383995 <STATE-OF-INCORPORATION>MN <FISCAL-YEAR-END>1231 </COMPANY-DATA> <FILING-VALUES> <FORM-TYPE>10-Q <ACT>34 <FILE-NUMBER>000-53713 <FILM-NUMBER>181171908 </FILING-VALUES> <BUSINESS-ADDRESS> <STREET1>215 S CASCADE ST <STREET2>PO BOX 496 <CITY>FERGUS FALLS <STATE>MN <ZIP>56538-0496 <PHONE>866-410-8780 </BUSINESS-ADDRESS> <MAIL-ADDRESS> <STREET1>215 S CASCADE ST <STREET2>PO BOX 496 <CITY>FERGUS FALLS <STATE>MN <ZIP>56538-0496 </MAIL-ADDRESS> <FORMER-COMPANY> <FORMER-CONFORMED-NAME>Otter Tail Holding Co <DATE-CHANGED>20090618 </FORMER-COMPANY> </FILER>