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Just as when working out gross rental yield, you'll need the total rent you collect from the property in a year. Multiply weekly rent by 52 and monthly rent by 12 to find the annual amount. For example, if you rented a condominium for $2,000 a month, your annual rental income would be $24,000. For net rental yield, you'll also take into account the other costs of owning the property. Include all fees, mortgage payments, interest, taxes, insurance premiums, and other costs associated with the property for the year. Typically these will be monthly expenses, so don't forget to multiply them by 12 to get the annual total. For example, suppose your annual rental income was $24,000 and the condominium unit cost you $900 a month to maintain. Your annual cost to own the property would be $10,800. When you subtract $10,800 from $24,000, you get $13,200. The current value of the property is not your mortgage payment, which likely includes interest, taxes, and other fees. Instead, look at the value of the most recent appraisal of the property. That's the amount you could likely sell the property for. For example, suppose the condominium you own is worth $250,000. You have an annual rental income of $24,000 for the property, which decreased to $13,200 by the costs of owning the property. When you divide $13,200 by $250,000, you get 0.0528. Net rental yield, like gross rental yield, is expressed as a percentage of the value of the property. To get that percentage, take the decimal you got when you divided the annual rental income less costs by the current value of the property and multiply it by 100. To continue the example, if you had annual rental income less costs of $13,200 divided by $250,000, you would have a net rental yield of 5.28%. This is considered a relatively low rental yield, but might still be sustainable depending on the location of the property or your reasons for owning it.

Summary:
Start with your total yearly rental income. Subtract your annual expenses from the rental income. Divide the result by the current value of the property. Multiply by 100 to find your net rental yield.