Oh, yes, tax liens are different in every state -- and sometimes they differ from county to county! I can only tell you what works in my county and the surrounding several counties.
First, the assessor's office in each county gives me the LEGAL address of all properties with tax liens. They all have a pre-printed list available for anyone who walks in and asks. Free. MOST of the "legal addresses" don't show street addresses. So you slog down to another department where you look up the legal address in the equivalent of a "reverse directory", and get the street address. Then you drive around and inspect the various properties.
I like to talk to neighbors in residential areas. Sometimes they'll tell you the owners are involved in an acrimonious divorce, or the owner died and the kids are fighting over the property. The more info you gather, the better the decisions you make.
Here, the owners have only 3 years to pay the taxes before the property is seized. If they pay the taxes, you get your money back plus 13% interest.
Meanwhile, if the property is sold, you get your investment back, plus 13% interest (which is free of state tax, but not federal tax -- it's taxable income, unless you're doing this with IRA funds -- which might be possible,
I'm not sure, you'd have to talk with a tax expert about that).
Taxing authorities I deal with do NOT allow "partial payment" of taxes UNLESS it's a monthly payment that has been agreed to and approved, "escrow", on this year's current taxes.
In areas with high taxes, you'd be investing thousands.
Here, they are NOT auctioned. If the back taxes are $1300, you give the assessor's office the $1300, and you earn 13% interest on the full $l300.
Once a year the local newspapers print a list of all properties with past due taxes. Then there is a flurry of activity. But they are actually available year around.
Here, tax liens have priority over any other lien. You don't really want to end up owning a property worth $4,000 with $15,000 in other liens on it, because as the property owner, you then owe all those liens. However, the same county office here that gives me the tax liens also can tell me of any other liens on the property.
It is REAL, slogging, HARD work. You must do your homework, find out exactly how it works in your area. In big cities, you'll be going up against real pros, who pick and choose and leave the dogs for you. In rural areas, much less competition, and the competition tends to be less sophisticated.
I find the safe and guaranteed 13% return to be worth the work. I'm too old to take the risk in the stock market.
I would suggest taking some rural shops and fit time in your schedule to drop in at the rural courthouse and suss out the assessor's office!
I'd also like to ask OP how she hides these funds from hubby at tax time? Surely they file taxes together, so he must be aware she has income?