Accessory Dwellings
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ADU breakeven calculator
You can download this MS Excel calculator to figure out your likely breakeven number in years. Read more about the ADU breakeven calculator here.
To use the tool, simply enter your values for the cells highlighted in green and blue by double clicking on the cell in the ‘assumptions’ tab. The bottom cell in yellow will show you your ‘Number of Years to Breakeven’. You’ll need to make some assumptions about the cost of construction, the property tax impacts, and the rental income rate.
You can also view (and modify) the core calculator assumptions.
Accessory Dwellings 
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I downloaded this, but the worksheet appears to be password protected so I can’t enter my values. Any ideas? Thanks!
Once you’ve downloaded the Excel spreadsheet, the password to unlock the spreadsheet is listed in Box C1. Let me know if that doesn’t work for you.
i AM NOT SEEING THE PASSWORD. Is there a more up to date version of this calculator kicking around?
Hi, We went on the Spring ’15 ADU tour and loved it! Do you know of any CPAs based in Portland, OR that are to some degree ADU/Real Estate-savvy? I asked my real estate agent and she told me to ask here….My conundrum is whether or not to build an approx. 670SF detached ADU on a higher value double lot with house and oversized garage. We may sell (downsize) in 5+ years and ‘breaking even” is not the issue. The City of Portland will likely want business tax payment on the SALE of the property (business income gains) and I am trying to find out (that is get a rough idea) how that tax amount is determined. If it is based on the entire property value then that is something that needs to be considered. I think it would be fair if the tax were applied to that portion of the property used for the ADU, but I don’t know. Similar to an in-house business using an office in the house, for example. Any CPA suggestions would be greatly appreciated. I understand that it would NOT be a recommendation. Thank you!
One local Portland CPA who might be able to help vet this issue is Leslie Yudin,
Up Front Accounting Services Inc., (503) 287-6680 Office.
But I suspect that getting input from an appraiser (or real estate professional with those skills) might be more important information to get. Tax implications matter, of course. But they’re likely to be relatively small potatoes compared with the fundamental economics of the project (ie. how much it costs to build vs. how much value it adds to the property).
Why does this calculator care about the distinction between total costs and starting ADU value?
Thank you for the spreadsheet! I have a Detached Accessory Dwelling Unit/rental and I’m wondering how others have had these insured by their insurance companies. Was it through the homeowners insurance or a separate Dwelling Fire policy? I’m getting different answers from different agents (even in the same agency) and very large discrepancies in quotes. Thanks in advance!
For me, the general liability was covered in my homeowners policy, but there was an extra fire policy for the new building. My company is Amica. -martin