People are going to be looking at vacancies and loss of income and challenges paying taxes, mortgages, ets. 

@John BakerSounds like I may need to prepare for a period time of vacancy, longer than normal, maybe?

I'm familiar with that area and have noticed a very small vacancy rate.I've been hearing BRRRR is difficult around hear from several people.

Good market would be growing population, diversified economy, median income >3x median rent, increasing rent trend, low vacancy, low crime, close to employment & public transportation.

Also remember leasing fees for vacancies that run on a commission of one months rent to market, show, screen and lease. 

-if prices do not rebound we will need a plan beyond that and it will not be pretty-this can and will hit the rental market in a variety of ways and here are a few potential issues i see.1. higher end rentals could see prices drop or vacancies increase as this type of downturn could hit middle to upper income families that have not budgeted or who see their jobs or incomes decrease as companies tighten their belts and cut salaries or even lay off more folks.2. low income rentals would see more evictions and more late rent payments and potentially small decreases in price - while many of the low income families in town do not work for the oil and gas industry they do often work in service industries that are frequented by oil and gas folks or depend on programs that are subsidized by oil and gas money in our state budget. 3. property prices and values - prices are being driven up on investment properties mostly by out of state investors as there are very few areas where you can get a "decent" property for under 100k and we are still one of them. 

.$950:  GSR$48:    Vacancy (5%)$143:  Repairs and CapEx (15% combined)$95:    Management (10%)$50:    Insurance$50:    Property Taxes$374:  Debt Service (20% down, 4.25%, 30-year)   =$191/month cash flow (12% CoC ROI on DP)Now imagine this is a quadplex with lower per-unit costs and some efficiencies of scale (a few more expenses, too).

How did you arrive at a 3% vacancy.

Our vacancy within 30 days went from 30% to about 75% across our 5 units. 

To follow up on what @Guifre Mora said, here are the main things I would look at since it is a 3 unit and a quick breakdown for analyzing it.IncomeRental income  -Vacancy/Loss to lease (depends on area but 10% of income would be a good general figured to go with)Other income (if applicable, might have coin washers/dryers since it is near a college)Total IncomeExpensesProperty Management Fees (10% of income)Repairs and Maintenance (10-15% of income)Real Estate Taxes (can find on county's tax assessor's website)CapEX/Reserves (Can vary greatly based on condition of the property, roofs, HVAC, etc.