Deductions & credits

For my 2018 filing I used December 2017-2018 as my qualifying period. I was going to use December 2018-December 2019 as my qualifying period for my 2019 taxes, however I returned in October 2019.

 

Can I used October 2018-October 2019 as my qualifying period for my 2019 taxes even though Oct - Dec 2018 was used in my previous qualifying period? I thought qualifying periods could not overlap?

 

Thanks again for you insight!