My two sisters and I inherited the home in 2010.
2010 Fair market value of home + land: $160,500
Addition to home (Kitchen/den extension): $40,855
Repair/improvements done during sale negotiation: $14,000
This all totals up to $215,355
House was sold for $223,500. Thus total gain (subtracting the above) was $8,145, or $2715 to each of us after all costs are accounted.
The 1099-S only shows gross proceeds of $223,500 for the sale, of which my allocation is $74,500.
How do I enter relevant numbers to show all this and report my net gain of $2733.33?
You would start by reporting your basis. Your basis is the Fair Market Value of the home when you inherited it plus improvements. The basis is subtracted from your share of the sale to arrive at any gain. Your basis is 53,500 FMV plus improvements 18,285 for a total of 71,785. Your portion of the sale is 74,500, so you had a gain of 2,715.
The 1099-S should report the breakdown of your share only. You would report the 1099-S and the basis of 71,785 for a gain of 2,715. If the 1099-S is not reported correctly, you can ask for a corrected copy.
IF the property was used as a rental at any time after you inherited it, the depreciation taken, or could have been taken, would need to be recaptured.
According to the IRS:
For multiple transferors of the same real estate, you must file a separate Form 1099-S for each transferor. At or before closing, you must request from the transferors an allocation of the gross proceeds among the transferors. The request and the response are not required to be in writing. You must make a reasonable effort to contact all transferors of whom you have knowledge. However, you may rely on the unchallenged response of any transferor, and you need not make additional contacts with other transferors after at least one complete allocation is received (100% of gross proceeds, whether or not received in a single response). If you receive the allocation, report gross proceeds on each Form 1099-S accordingly.
You are not required to, but you may, report gross proceeds in accordance with an allocation received after the closing date but before the due date of Form 1099-S (without extensions). However, you cannot report gross proceeds in accordance with an allocation received on or after the due date of Form 1099-S (without extensions).
If no gross proceeds are allocated to a transferor because no allocation or an incomplete allocation is received, you must report the total unallocated gross proceeds on the Form 1099-S made for that transferor. If you do not receive any allocation or you receive conflicting allocations, report on each transferor's Form 1099-S the total unallocated gross proceeds.”