Good ranking FS, I’d have to agree with the rankings. And it looks like your portfolio covers five of the six! Some people consider real estate passive will others classify it as active. But every scenario is different, whether you are doing all the maintenance and managing yourself, or you are contracting out a lot of the work. Obviously it takes a lot more time and effort than purchasing a 36 month CD and “setting it and forgetting it.”
I’ve never invested in real estate (except to live in), but am always intrigued by communities like FS who seem to have such a passion for it. My intrigue stems back to my earlier comments that the long term trends in appreciation in real estate are simply not very competitive versus equities, despite what Robert Kiyosaki had to say in his book, Rich Dad, Poor Dad.
One of the things I'm surprised your article doesn't mention is the tax advantages of this type of investment. The depreciation and rehab costs (purchasing distressed properties) can be huge deductions to ones income taxes, which none of the others have. Then, along with the appreciation of real estate, this passive income investment outperforms the notion of maxing out my 401k as well.
In many instances, a business project consumes far more resources than meets the eye. Assume you are running a dog grooming business from the first floor of your two-family house and that your daughter is helping you over the weekends. The business is making $50,000 per year and you want to know whether this represents a positive or negative residual value. In this case, you must deduct from $50,000 all opportunity costs which include the money you would make if you rented the first floor of your house to a business; how much you plus your daughter would earn if you invested the same amount of time and effort into a regular job; and how much the total assets owned by the business would return every year if they were sold off and the cash proceeds were held in a bank account.

Who cares, especially when very conservatively, the ultimate passive income includes a six digit or more base lease, plus an estimated additional six digits or more for rate increases and another six digits for more for various smaller and one bigger technology increase at 25 years. All four (base, rate, smaller and mega technology increases) combined, certainly could yield much more depending upon inflation, rate increases and technology increases?
Passive income differs from active income which is defined as any earned income including all the taxable income and wages the earner get from working. Linear active income refers to one constantly needed to stay active to maintain the stream of income, and once an individual chooses to stop working the income will also stop, examples of active income include wages, self-employment income, martial participation in s corp, partnership.[4] portfolio income is derived from investments and includes capital gains, interest, dividends, and royalties.[5]
The reason I consider dividends artificial and believe they don’t matter is because you can just as easily reinvest your dividends. If a stock is worth $100/share, I don’t care if it issues a $1/share dividend or if the share price instead increases to $101/share – either way, I have the same amount of money, because there’s no difference to my net worth whether I take the dividend or sell part of a stock.
Investing in rental properties: Another form of real estate investment, rental investments (i.e. becoming a landlord) could steer you down the passive income path of steady monthly rent checks that you can use to pay off a mortgage loan on the rental property. After the mortgage is paid off, those monthly checks go right into your bank account -- potentially for years to come. 
The second form of residual income, passive income, is often a vital part of wealth creation. There are only so many hours in each day, and when a person trades hours for dollars, there is a maximum amount of income that person can earn. For instance, if a person earns a specific amount each hour, there is a limit to how many hours are available to work. Once they reach that maximum amount of time, they cannot earn more money.
Many people talk about passive income and create the impression that you never have to do anything to keep that income going. The truth is that you will normally have to keep your eye on things if you want it to run smoothly. For example Richard Branson doesn’t run any of the 400+ companies he started but he goes over the numbers each day to make sure they’re performing well and calls the CEO if there are any problems.
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