The point of the prior experts is the following:
If there was a life estate in writing, you would receive the property with a fully stepped up basis, and likely owe no capital gains tax assuming the home does not increase in value between the date of death and the date of sale.
However, even if there is no life estate in writing, it might be implied by the facts and circumstances, and that also gives you a stepped up basis. The problem with an implied life estate is proving it if audited--you might have emails with your parents discussing their reasons for adding you to the title, for example. But just because it is harder to prove doesn't mean it is not valid.
If we assume there is no implied life estate, then you need to calculate your basis. Let's assume the mobile home cost $30,000 and there are no adjustments like improvements. When your parent gave you a half-share, your cost basis in that half-share is $15,000. Let's then assume the home is worth $50,000 on the date of death. You inherited the other half with a stepped up basis of $25,000, for a total basis of $40,000. So whether you owe capital gains tax, and how much, depends on the selling price compared with your basis. (You can also subtract the real estate commission and certain other closing costs, see publication 523 on page 8. https://www.irs.gov/forms-pubs/about-publication-523)
I want to emphasize that is the worst-case scenario. So what I would do is figure out the tax if you assume you have an implied life estate, and also as if you don't. (Depending on your financial situation, the capital gains tax could be zero, 15% or 20%.) Once you know how much you will save by claiming an implied life estate, you can decide whether that savings is worth a professional consultation as recommended.
I am also of the impression that mobile homes don't really appreciate in value, so you might have a capital loss rather than a gain, no matter how you figure your basis.
The gain is reported in the year of the sale (2024).
