Repairs/Improvements made in 2020, but paid in 2021

[Brendan Carlson]

For one of my rental properties, I had a contractor do 2 repairs (small roof repair, replaced four windows) and 4 improvements (added support beams in crawlspace, added gutters and downspouts, added basement access door, added soffit).

The work was completed in December 2020. However, I paid in January 2021 via check.

Would I expense & capitalize these repairs & improvements on my 2020 taxes or 2021 taxes?