Are you making money on your investment property?
Is it an asset or a liability? Let’s do the numbers!
Is my property an asset or a liability?
Is your investment property actually an asset? The Donegans have a simple definition for an asset: does it put money in your pocket?
So many of the people that come on Rebel Finance School ask us about their investment properties. Should I keep it? Should I sell it? What should I do with it?
For us it always comes back to the maths. Is it actually making a return? How much are you making? Not the back of the envelope type maths that says rent minus a rough guess of the expenses, the proper calculation to show what you are making.
If you are making a monthly loss on your rental property, what are you hoping for? After ten years, the value will increase, and you can sell it for a huge profit? Have you done the sums to know if you are putting in £200 / $200 a month for ten years how much will it really have to have gone up by to make sense? So many people don’t know the numbers for their property, and this is the first step! Let’s look at the cold, hard maths and the data and make data-driven investment decisions. This calculator will help you see what the return on your equity in the property actually is.
What is the opportunity cost of my property?
There is an opportunity cost wherever you deploy your capital. What I mean is that you can only invest the Pounds or Dollars you have once. If you invest in property, you are actively choosing that over index funds.
The opportunity cost is what you could be doing with your hard-earned cash instead. In the UK, at least, it is difficult to own property in a tax-efficient manner, but you can own index funds in a tax-advantaged account (ISAs, SIPPS, LISAs, Etc.)
What we need to know is what is your actual return on the property and then compare that to what you could have been getting in an ISA (taking into consideration all the costs and tax)
Since we started investing in index funds (as of June 2024), we have earned a 12.6% net return annually. That is the opportunity cost of having properties. Our cash could either be in index funds or property, not both at the same time.
The first step is ALWAYS to understand what you already have and then secondly to compare it to other options. So, let’s get down and dirty with the sums and work out if your property is an asset or not.
What’s the return on your investment property?
A lot of our Rebel Finance School attendees ask if it’s a good idea to invest in property. Or they want to be really clear on what return on investment or return on equity they’re getting. This can be tough to figure out, so we built this calculator to help you do it. You can use this calculator to analyse an investment you already own, OR you can use it to assess a potential investment.
Investment decisions should be based on maths and logic, not emotion. So, let’s get into the numbers.
A few things to know before you get going!
- It is best viewed on a desktop. If you’re using a mobile device, we suggest turning your phone to landscape to see all the elements. We are working on a mobile-friendly version!
- This calculator does not allow for tax since everyone’s personal circumstances are different. After you have your return, then consider your own tax situation to truly understand the returns after tax
- If you are working on a mobile phone, you may have to double-tap the cells to write into them.
Enjoy using the calculator, and then keep reading for some final thoughts. We want your feedback, so see the form at the bottom for questions and comments!
The Excel spreadsheet below can be downloaded here
Property is a business
Investing in property can yield a good return. If you’re thinking of buying a property to rent out, make sure you do the numbers to work out the estimated return. I say “estimated” here because we can guess what the costs will be with the property, but we don’t know exactly what will happen or what unexpected costs will come up. You’re renting to people, and people do unpredictable things sometimes!
When most people work out the return, they assume they will be able to rent out the property 100% of the time. This may or may not happen. We have owned and rented out three different properties. One of them has always had a tenant in it. The second one has always had a tenant in it, BUT they stopped paying rent for a few months during the pandemic. And the third one was empty for 5 months whilst we struggled to find a tenant. This is why we’ve included the void assumption in our calculator: to allow for the fact that the property will probably be empty at some point while you own it.
Make no mistake, owning property is a business. Even if you hire a property manager or lettings agent, you are still ultimately responsible for the property and looking after your tenants, so there is still work involved. We used to own properties, but we sold them all. At this stage in our lives, we’d rather be passive in our investments and active in our lives. This is why we invest in low-cost index funds, so we can spend our lives having fun and prancing about on the beach rather than managing our investments.
Return on Equity
The reason return on equity is important after you have had the property for a while is because that equity could be doing something else for you if you didn’t have the property. You might have only made a £25,000 investment in terms of the deposit, but after 5 years invested, you might have £125,000 equity in the property.
When you are considering your return it is critical to work out the return on equity. This is because that equity that has been building up could be working for you somewhere else if you sold the place and invested it in a different way. You might be getting a fabulous ROI but an appalling ROE, which is the position we are in at the moment.
Our ROE was only 4% on our properties. We get a far better return in a low-cost index fund instead and have less work to do.
Feedback please
Please please please let us know what you think of the calculator. Are there bits that don’t make sense or you don’t understand? Are there ways you think we could improve it. Please tell us!

Thanks Sam, we have messaged you by email and checked it. Please reply to the email Katie sent
This was really interesting. I put my numbers in for a triplex with a 5% vacancy and then I counted up the actual months vacant, whether for renovations, evictions (not paying months), or otherwise empty months and it went from 9% ROE to 6.2% ROE. Thank you for the nifty calculator tool! Congratulations on the medal, 5 steps away from Knighthood! I also thoroughly enjoyed your talks at Econome 2025 and 2024!!
Traci, just read this out to Katie. how cool! YAY. Love that you did the maths on the properties. Such an important exercise. Were you at Econome? Did we manage to chat!?? We had SO much fun at that event. You are amazing. THANK YOU for writing to us. Alan and Katie
We have just found out Microsoft has changed how their embedding spreadsheet works. it is so annoying. We are working to find a new solution and will have it up again soon! Sorry
Wendy, We have just found out Microsoft has changed how their embedding spreadsheet works. it is so annoying. We are working to find a new solution and will have it up again soon! Sorry. I am so sorry. Will have it ready again soon
I’ve added a download link just above the broken embedded spreadsheet :( – https://rebeldonegans.com/wp-content/uploads/2025/05/Return-on-equity-calculator-1.xlsx
I’ve added a download link just above the broken embedded spreadsheet :( – https://rebeldonegans.com/wp-content/uploads/2025/05/Return-on-equity-calculator-1.xlsx
Hey Rachel, I am sorry Microsoft have changed it. You can download it to get it and use it off line! Alan
How do you calculate this if you’ve had the property for years and you don’t have the original paperwork relating to costs etc please?
Hey Andrea, just do it for the last years costs and work out the ROE for the last year for now. That will give you a good idea for now. You can also guess at the rough amounts such as solicitors fees. You could get some averages from online to give you a rough estimate which is better than nothing! Does that help unlock you? Alan
Thanks for this question an answer i was wondering the same :). With this in mind would it be appropriate to have a tab with ROE annually? i have huge costs this year (extenting leasehold :( :( :( ) selling at this point would be illogical from a finance POV. but maybe an ongoing picture would be helpful? Many thanks for all the work you do.
that is a great idea as yes some years will be good and some bad, some with voids and others rented out all the time so this make sense to look at it over the long term yes. Averaging all those up and downs out!
Kia ora Alan and Katie,
This is a fantastic tool! I have done the calculations for our rental property in Auckland, which used to be our home, and the ROE is 1.8%! We listed it for sale earlier on this year, but we didn’t receive any offers until we had re-tenanted the property. There was a perfect window for a purchaser to have acquired our property when our tenant vacated the property. However, there weren’t any offers forthcoming, such is the market, so we instructed our property manager to list the property as being available for a new tenant. We’ll reconsider selling our property in 2026. We have other property (native bush, grazing and a site with a rental property) in the Hokianga (a 5-hour drive north of Auckland) which takes a lot of time and effort to manage. Though this whenua (land), wasn’t bought for a ROE but to keep it within the whānau (family). This is a whole other kaupapa (subject) and my husband and I are working out options for it generate an economic return for us. Once again, thanks to you, Katie and the Rebel Ninjas for this amazing course and a big mihi (thank you) to acknowledge the time and effort it has taken and continues to take to produce such as outstanding free resource. Ngā mihi Charmaine
Hi Katie and Alan,
Do you own a property that you live in and if you don’t how do you live month to month, I have 2 kids so need stability and need a decent size house which comes with its own costs (council tax being the worst)
Hey Gary! Great question. No, we don’t own a property anymore—we sold up and now live in Airbnbs and hotels around the world 🌍. All the equity that was in our home is now working for us in investments. It gives us flexibility, freedom, and the ability to live life on our terms. Stability looks different for everyone, and this setup works beautifully for us. Keep exploring what works best for your family and your journey to financial freedom and you are so right, council tax, other expenses can be super high. We all have different situations and requirements!
Peace and Pineapples 🍍✌️ A&K
Wow. This has been most illuminating. ROI 6.8%, ROE 4.6% on both BTL properties with no mortgages on each and held in a limited company. What a conundrum. They have both been let 100% of the time since we bought them in 2018 as there is very little to rent in our village. They are very low maintenance and are not time consuming and we are able to draw from the company by way of repayment of directors’ loan (the properties were originally bought with mortgages on our family home as that is mortgage free and the financing was lower), which is currently funding our daughter’s university education.
I was considering a third BTL but having carved out a 68% GAP following this amazing course and having some serious conversations, with 5 years to go until retirement at 52, I am thinking ETF all the way?
I have spent my entire adult life thinking I was good with money, I’ve reframed that to ‘I am excellent at budgeting but I am yet to be derive the most efficacy from our money working for us’. Beast mode needed for the next 5 years.
Thank you so much Katie and Alan.
Rebecca, what a brilliant breakdown! LOVE that you worked out the ROE on both properties and understand them now. THere may be some great tax efficiencies the way you are doing it. You’re clearly switched on and thinking deeply. Beast mode activated for the next 5 years sounds like a plan! ETFs can be a great way to simplify and diversify—especially if you’re aiming for FI with flexibility plus the ROE in comparison can be 10-12% a year. The properties have got capital growth too, do you know how much that has been over the past years? Keep questioning, keep learning, and keep rocking it.
Peace and Pineapples 🍍✌️ A&K
Hi Alan and Katie, I have loved your course 😊
Filling this in is blowing my brains! Note sure how to cater for the following on the template:
* Interest only loans (surely it would be understating things if I just put the monthly interest payments in, but how do I calculate a more realistic amount?)
* Significantly reduced mortgage balances due to putting a lot of our own cash into flexi and offset loans? (put all this cash into the template as Deposit/down payment?)
* For the how much do I owe on the property, do I put in the full loan amounts (since they are interest only) and do I use the amount before or after the offset of our cash in the mortgage accounts?
I am sure that it is very easy to double count things!
Looking forward to hearing back from you when you can.
I hope that you are having an awesome time in Brazil 😊
HI Katie and Alan, I’ve just done the maths and found out that I have a ROI of 8.2% and ROE of 1.7% on my rental property. The ROE seems very low even though the property has appreciated massively and the outstanding mortgage costs are relatively low. Not sure what to make of this…I might have to rewatch the video!
Maria, great work crunching the numbers! That ROE is low. The other thing to do is to work out how much you have made from property appreciation minus costs. On a cash flow basis that is a super low ROE but take into account the property price accumulation and see what you get. It might be time to revisit the calculator and see if the equity could be working harder elsewhere. Rewatching the video is a great shout. Keep going—you’re doing amazing! Let us know if we can do anything at all to help!
Peace and Pineapples 🍍✌️
The Donegans
I bumped into someone walking their dog the other day who told me ‘I MUST GET INVOLVED AND LISTEN TO THE DONEGANS’ as it will be one of the best things I will ever do as far as money is concerned! I’ve just started ‘the journey’ and love it!
Clive that is amazing. I can’t believe a fellow dog walker told you to watch the course. That is insane. Thanks for joining us on this cool journey! Let us know how you get on! ALan
Thanks, great information. I love your content. Great job guys!
I have a rental property in Bristol that has an ROE of only 2.7%. Unrelated to this, I am also due to receive some inheritance from my parents imminently of around £200,000.
The money from my parents will go in my Vanguard General account and be drip feed into my ISA and SiPP every year. This means that if I sold my property, the proceeds wouldn’t go in a tax advantaged account (just in my Vanguard stocks and shares general account) as I would already have maxed out my ISA and SIPP allowances.
In this kind of situation, does the balance still tip in favour of keeping it in a Vanguard general investment account vs keeping the property? My intuition is that yes, property is the worse option and my returns are likely to be much higher even in the general account.
Gaya, what a lovely message. YAY and well done working out the ROE on the property. That is a pretty low return and even after you factor in capital growth it probably isn’t going to beat an index fund.
The question about putting the money in a GIA and then every year doing BED and ISA and BED and SIPP and whether it would beat 2.7%. If you average 10-12% over the long term in a global index fund then it would still be better. Let’s say you are a higher rate tax payer and you get 10% return, you pay 40% of that to the gov and you are still left with 6% which is better than you current returns. This is super crude and not very accurate but it gives you an idea of how I would think about it. You have annual CGT allowance which you can max out, you get the tax back on income putting it into a SIPP. I think you would be far better off…
Did that help at all?
Alan
Hi guys, I hope you’re both well. I just read this article, expecting to see a calculator at the end, but there’s nothing there. Am I missing something?
hey Adam, half way down it says download the spreadsheet here: it wasn’t that obvious. our fault. Sorry. Can you let us know if you find it! Alan
My brother and I co-own a cottage which we let out as a residential property. We were gifted it by my parents more than ten years ago (they inherited my granny’s cottage so wanted to offload their own cottage early to avoid inheritance tax).
Because we didn’t pay anything for it, our return on investment is going to seem amazing- indeed almost all of the costs associated with the cottage come from the rent it generates. It doesn’t generate a huge income, a)because of its size and where it is and b)because we’ve both been renters in the past and wanted to charge a fair market rate for it.
Looking back, I suppose the ‘clever’ thing would have been to have always invested our rental income in an index fund- so that it would be making us money whilst also appreciating equity (which I think it will have done, certainly since my parents bought it). But I can’t shake the feeling that the idea of ‘time in market’ means we should just sell up (would be subject to capital gains tax, presumably on the whole selling price as we didn’t pay anything for it, unless some ‘value’ was ascribed to it when we were given it) and invest the whole return in a Donegan-approved way.
Hey Helen, have you worked out the return on equity? not the return on investment. We want to know how the cottage is performing now. So take the amount of equity (after tax if you need to pay tax when selling it) you have locked away in these bricks and work out the return on that money. That is the true comparison of selling it and investing in the market instead… Lumen you seem AWESOME. Loved reading your message and I hope we get to have breakfast together one day! ALan
Hey team, I’m excited to use the ROE tool but do not have xcel and only access to Google sheets. Is there a chance you’ll be making a google sheets version of this? thank you, loving the RFS 2026 :)
Hey Penelope, there is a free version of excel if you use it in a browser for now and we are planning a google sheets version at some point. maybe for now you could use the comparison tool.. that would give you a great comparison https://rebeldonegans.com/finance/resources/freedom-fund-audit/ Sending happiness! Alan
For the mortgage payment, should this only be the interest on the mortgage? The part of the payment that is for capital repayment is effectively going in to your pocket?