Which was it? Did you "receive an inheritance" Or did you brother "sell a house and give you a third"?
Sale of Inherited Home. Sales of real estate are usually reportable on your tax return, especially if a form 1099-S is issued. There will most likely be no capital gain and therefore no tax. Any capital gain would be on the difference between what the house was worth on the date of the decedent's death (your "cost basis") and what the house sold for. You would report only your third of the sale and your third of the cost basis.
If you brother was the owner of the house (e.g. only he inherited title), then you do not report your third as income. You only received a gift and that is not taxable. Your brother may have to file a gift tax* return.
*"Gift Tax" is somewhat of a misnomer. Even though a gift tax return may be required, very few people ever actually pay federal gift tax. The purpose of the gift tax return is usually only to document a reduction in the allowable estate tax exemption.
See https://turbotax.intuit.com/tax-tools/tax-tips/Tax-Planning-and-Checklists/The-Gift-Tax-Made-Simple/...
