Fire loss in Nov 2017 on a rental condo. I didn't have insurance. I paid out of my pockets to fix the fire loss: $6000 in 2017, and $8000 in early 2018.

Should I enter Casualty Loss "Cost Basis" of $14000 in tax year 2017 (Fire happened in 2017)?
Or should I split? If I split, would 2018 tax year know that I'm entering an event that happened in 2017?