Purchase or the remaining share of a primary residence

Earlier this year I purchased the remaining 1/2 of the house that I have lived in for 28 years.  I purchased the property with my partner in 1996 with each owning 50% at the time.  With this purchase from earlier in the year, I now own 100% of the property. 

 

What tax implications are there for the 2024 tax year?    If I hold the property for a few years and later sell it, what is my cost basis.  Is my cost basis considered to be the amount I paid in 2024 or the combined amounts of 1/2 amount I paid in 1996 plus the amount I paid in 2024?