Tax implications from sale of Transfer on Death home

Hello! Trying to figure out what to expect for taxes on the pending sale of my deceased father's house in Ohio. Because I'm self employed I need to figure this out so that I can pay enough estimated taxes this year.

My father died in Nov 2025, and his home was Transfer on Death to me. I'm about to sell the house and unsure how this will work when it's time to file 2026 taxes. Both myself/the house are located in Ohio, no mortgage or liens. As I understand it, I should just need to report any capital gains from the sale on my 2026 return.

So, how do I determine value at death for the Capital Gains step-up basis?

Because the home was TOD, there was no valuation process like there might have been with an estate/inheritance (he had so few assets we actually went through mini-probate.) We have made limited improvements (painting, vinyl floor, a plumbing fix) and I'm unsure how much those impacted our final listing price.

This has all been overwhelming and I really appreciate any help.