I  Income:  The amount of property you can buy will be dependent on your Debt to Income ratio.  

Because of the nature of a tax lien, it would be difficult to obtain financing from a commercial lender secured by the tax lien itself.  

There may be a property tax benefit to leaving pieces.

Not much if any attention is paid to the guarantors, credit, income, etc. 

Approval is based on rental income, not personal income.

@Frank FloresInvesting in delinquent tax sales in Houston can be profitable, but it comes with risks.

For example, I mention that every adult must pay a $30 application fee, pass my credit/criminal background, make a combined income of 3x the rent, and whether or not the property accepts pets.

Figured there would be a few data points left out of the equation' that I would need to circle back with :) .There are additional units not rented at this time which could be rented to increase the income.

They are not experienced real estate investors, they are retired and looking to create additional income. 

You are converting their tax free gain in to a taxable gain.