Hello again Customer,
The debts that you had to pay off such as taxes, insurance and funeral costs have no affect on figuring any gain you had from the sale of this home.
If the home was appraised at $450,000 at the time of your mother's passing, then $450,000 would be your starting basis. If you then made repairs such as new roofs, plumbing repairs, etc., you would add the cost of those repairs to that basis. So as an example, if the repairs that you made cost you a total of $25,000, then your basis actually becomes $475,000. If you then sell the house for only $470,000, you actually had a loss of $5,000 and so you will owe no tax.
Using another example -- if the repairs only cost you $10,000, your basis now becomes $460,000. If you sell the home for $470,000, you have a reportable gain of $10,000 which is split equally between the siblings. If there are 4 of you, then each of you would report a gain of $2,500 and your maximum tax at 15% would be $375.
From the extent of the repairs that you say you have made, I would say it is very likely you spent at least $20,000 or more on those repairs. So if that is the case, that will bring your basis up to more than the selling price, and you will owe no taxes on the sale of this property.
Thank you Customer