Transfer of Cost Basis for Gifted Real Estate

[hcjontax]

Below is a timeline of a property that was gifted and sold between family members from 1998-2020:

1.) 1998 - property purchased by dad for $120,000
2.) 2018 - property gifted to son for $1
2.) 2020 - November - property gifted to mother for $1
3.) 2020 - December - property sold by mother for $340,000 to buyer outside family.

Question is - when the mother files her 2020 return, does she have a $120,000 cost basis and a $220,000 short term capital gain? The reason for moving the title to the mother was because she has a -$170,000 short term capital loss, which would be used to offset the gain.

Also, if there were property improvements done by the father before 2018, but no documents that record this, can we estimate $30,000 was used to improve the property over the 18 year period, and raise the cost basis to $150,000?

[M-MTax]

Question is - when the mother files her 2020 return, does she have a $120,000 cost basis and a $220,000 short term capital gain? 

She has a $120k basis because it is all a carry over basis starting with the son and ending with the mother. BUT the gain is long term because of "tacking".