I assume you are talking about an existing tax liability, if this is the case then you can request an Installment Agreement with the IRS.To protect yourself against future tax liability you need to make quarterly estimated tax payments.

I thought that if I can "afford it" with my income and my score is high enough then the only limiting factor is that my mortgage/insurance/tax payments come out to less than roughly 40% of my monthly income. 

It does not matter what state the partners reside in.If your state imposes an individual income tax, taxpayers must generally report all their income (regardless of where it was earned) in their state of residency and pay income tax.

A quick search I did on the web for my own education revealed:A FIFA lien is a legal writ that has been issued by the tax commissioner against a taxpayer so that his/her property can be seized.

Not sure of how we or the InLaws could reduce or avoid paying a big old Capital Gains tax payment due to the difference in FMV from initial purchase to transfer.

Library cards are free (to users, thanks to tax payers).

They only want to collect the hefty penalties of 12-18% from the late tax payers as a way of getting high returns on low risk investments.

@Nathalie Hirsch There are certain 'safe harbors' and guidance from the IRS in connection with vacation home rentals.The IRS will not challenge whether a dwelling unit qualifies as §1031 exchange property held for productive use in a trade or business or for investment if: (1) the relinquished property is owned by the taxpayer for at least 24 months immediately prior to the exchange and a replacement property is owned for at least 24 months immediately after the exchange (the “qualifying use period”) and (2) within each of the two 12 month periods constituting the qualifying use period, the taxpayer must: (a) Rent the property to another person or persons at a fair rental for 14 or more days; and(b) The taxpayer’s personal use of the dwelling unit cannot exceed the greater of 14 days or 10 percent of the number of days during the 12 month period the dwelling unit is rented at a fair rental.

That says if you have lived in a house for two of the five years prior to sale then you can exempt $250K for a single tax payer or $500 for a married couple from capital gains taxes.But even if you don't live there a year you may have little, if any, taxable gain. 

The Treasury Regulations only require that the taxpayer have the intent to hold for rental or investment or business use.