Gently to some, pretty rudely to ones I think know better.

@Gabe Gordon @Jon Holdman   I just went through this exact exercise in Mississippi this year..

Call the realtor, before you send the offer through, and let them know you intend to exercise your right to be present. 

The government wants major upgrades or new construction within these zones as to the 100% of basis requirement.I know of a few clients that are planning on exercising the significant renovation part of the code by putting in a lot more than the purchase price. 

Live in one side for two years and exercise the primary residence exclusion = tax free.  

Collections and DelinquencySec 34.21 (e)(e) The owner of real property sold at a tax sale other than property that was used as the residence homestead of the owner or that was land designated for agricultural use when the suit or the application for the warrant was filed, or that is a mineral interest, may redeem the property in the same manner and by paying the same amounts as prescribed by Subsection (a), (b), (c), or (d), as applicable, except that:(1) the owner's right of redemption may be exercised not later than the 180th day following the date on which the purchaser's or taxing unit's deed is filed for record

You may also require a Phase One Environmental Assessment (EA) {which is predominately a paper exercise} depending on the requirements of your lender or the jurisdiction.I would reach out to @James Wise to learn more about the neighbourhood to see if it is a place you want to be.  

Usually, it starts when you buy the house at auction and record the deed.But I am hoping that for “struck off” properties the clock starts counting on the date that the sheriff tax deed is recorded.The actual wording of the Texas tax code is…“the owner's right of redemption may be exercised not later than the 180th day following the date on which the purchaser's or taxing unit's deed is filed for record.”

It was a fantastic exercise though -- I like looking at the possibilities and I like the mental work of trying to figure it out.  

It's a math exercise and you can use a BP calculator.