The factors on this are pretty large.They come down to how much money gets thrown off per unit.For most desirable locations in California, itu2019s impossible to rent the unit for more than upkeep, plus some margin for disaster.For example, say I have a small house in the $550K range:650-700 Square foot1 BR, 1BAThe property tax on it per year is about $8K, because property tax is very high in California.Say I put 20% dow, leaving a balance of $395K on a mortgageA 30 year mortgage at 3.92% (just checked), gives a monthly payment of $1,868/monthSo $22,416/year to mortgageLetu2019s round down, thatu2019s $30K/year outlay, not including maintenanceMinimum, I would need to charge $2,500/month rent, just to cover mortgage and government overheadI need 10% on top of that to cover the place potentially being vacant between rentals, thatu2019s $2,750/monthI need another 15% of base rent to cover maintenance u2022 things like broken appliances, gardening, paint, and so on, thatu2019s $3,150/monthNow thatu2019s a little priceyu2022 but itu2019s a standalone house, rather than an apartment, so that might just be doable.But itu2019s not throwing off anything for me to live on.What if I have other investments, and instead of taking a mortgage, which will eventually get paid down, I take a 1.9% loan against a line of credit?In that case, I (effectively) have an interest-only loan at $1,440/month, interest-only means I have no cash flow whatsoever.Further, this is going to tie up what I can and canu2019t do, as far as risk profile, when it comes to my other investments. Thatu2019s slightly painful, but maybe I can take it against the low risk portion of my portfolio.That gives me ($1,868 - $1,440) = $428/month positive cash flow. Or about $5,136/year total.But thatu2019s only a 1.3% return on the $395Ku2022 for which Iu2019m paying 1.9%. Iu2019m running net $0.6% in the holeu2022 Iu2019m bleeding $2,370/year.In theory, I should be able to make 10% on that capitalu2022 10% of $395K is $39,500.So net, I am facing an opportunity cost of ($39,500 + $2,370) = $41,870-.Now on the plus side, the low risk investments I have to take, instead of the higher yielding one, gets me u2022 letu2019s be generous: 5% on the $395K on which I took the line of credit. So I get 19,750+ back from that.So now Iu2019m u201conlyu201d losing $22,120-If I wanted the original $39,500 I would have gotten from investing in nearly anything but a rental house, Iu2019d need to charge another $5,135/month in rent.On that 650-700 square foot property.And people wonder why rent is so high in California.No.You will not be living off renting single family homes in any u201chotu201d areas in California, unless:You already own them outrightYou bought them before the costs went so high that your property taxes were through the roof because of the tax basis (the purchase price of the house)The only way you make a profit on this type of deal is as a long term investment, and the profit happens because of the price appreciation of the property, not because you are making any money as a landlord.That leaves multiple units.Itu2019s possible to make a profit on a multiunit building in a hot market.At a minimum, probably 6 units, better if there are 8 units.Anything less than about 8, and if a major expense comes up: youu2019re bankrupt.And you have to live in one of them yourself, you donu2019t get to live elsewhere.Obviously, as others have pointed out, the answer is going to vary wildly, depending on the location.Pick your location, run the numbers.Before you buy someone out on a multiunit building, talk to a tax accountant, and you will likely want a forensic accountant to look at the books for the location as a whole.Because there are probably long term tenants you canu2019t charge more rent, even as the state of California claims the ground under their feet is now suddenly worth more, I assure you u2022 it isnu2019t.Itu2019s worth what you can get out of it in cash flow, and that doesnu2019t go up, merely because the county (and in some cases city) is going to charge you more in property tax than the pervious owner.Good luck with your u201cretirementu201d!*(*) u201cFinger quotesu201d because if you are the on site manager, you will not be getting much sleep.