Should I pay down my mortgage or invest?

pay down my mortgage or invest This question came to my mind just after I and my wife had agreed to buy a house in London. The sale didn’t go as expected, but the question got stuck in my mind as if I’d bought it. “Should I pay down my mortgage or invest?”. Had we bought the place, what would we do with some spare cash every month?

Although this sounds like a “problem”, it is in fact, a very good situation to be in. Not only we have enough money to cover the mortgage payments but we also enjoy some extra cash every month. So if you’re in this place too, congratulations! We both are a step closer to financial independence.

There are two sides to this problem. The pure mathematical side and the psychological side. And because I’ve always trusted the numbers in my life, let’s start with that first!

Here’s a hypothetical scenario:

Mortgage details

Property cost: £300,000
Current retail-bank interest-rate: 2.3%
Outstanding debt: £150,000
Spare cash to invest or overpay: 20,000

Option #1 – Put all your savings towards paying off your mortgage

Let’s say you decide to put all your £20,000 towards your home equity. You call your bank and make a bank transfer the next day. This reduces your outstanding debt to a total of £150,000 – £20,000 = £130,000.
By saving £20,000 of debt, you have effectively saved £21,189 over a 5-year period if we add the interest in. Great! We saved money that would otherwise go to the bank.

Profit made over 5 years: £1,189

For the sake of the experiment let’s say that the bank will not charge you a fee for overpaying. My previous mortgage would charge me a fee for paying more than 10% of the outstanding loan every year.

Banks are obviously not charities and these £1,189 we have just saved is taken from the bank’s wallet.

Option #2 – Invest the extra £20,000

Let the mortgage run as is and invest the £20,000. Different investment options include buying a property or shares in the stock market.

According to the historical average of the US stock market, we can get a 7% return. Of course, this may vary from year to year and after accounting for fees. For example, the last 5 years were very profitable for the stock investor (16.82% annualized) but we all know what happened in 2007-08.

Now don’t get me started about your uncle that lost 30% when picking bad stocks 2 years ago…. Or people that have doubled their wealth in 2 years. That’s like playing the roulette.

This is why we take the average. By the way, the past 10-year average, including the financial crisis period was ~7%.

So our £20,000 invested in the stock market for 5 years would return a total amount of….. £28,051.

Profit made over 5 years: £8,051

So should I pay down my mortgage?

The maths say no. But numbers do not tell the whole truth. They have not accounted for the psychological burden of having a debt, a possible increase in interest rates, taxes on investment profits and one’s ability to invest.

Also, I haven’t met a single person saying they feel bad about paying off their mortgage. It just feels good! The following questions make it easier for us to decide.

Do you have a more expensive outstanding debt?

If yes, you should treat the high-interest debt as an emergency. Not an emergency, AN EMERGENCY! This 17.99% interest debt is seriously damaging your wallet and should be cleared off ASAP.

Forget about mortgage overpayments and investments and focus all your efforts on paying off this debt. A good way to start is to switch your mobile plan to £5.56 per month and to earn some side income if possible (try matched betting?).

What type of personality are you?

If you’re risk-averse then you probably find paying down the mortgage a better option. There is a psychological burden coming with every debt, and a great relief and sense of achievement when you repay the last cent. Some people – understandably so – prefer to be debt-free. There is no greater feeling than owing nothing!!

Talking about risk… note that paying down the mortgage gives you a GUARANTEED return of 2.3% (or whatever the interest rate is). There is no risk involved, no dealing fees to think about, no chance of losing a PENNY, whatsoever.

Investing, on the other hand, involves some risk. Sure, the risk can be reduced if you see it as a long-term game and you may even get back more than the expected return, but it’s all volatile.

If the stock market crashes and your extra cash is cut to half, will you still be able to pay the mortgage repayments or will you go into trouble? Are you going to remain calm when you see your wealth potentially cut in half? Even if you know that in the next 5 years it will grow back higher than the initial amount?

If you answered no to these questions, then maybe paying down the mortgage is a better option. Otherwise, you also risk becoming a victim of your own behaviour. That means, selling your investments out of fear when the worst happens (instead of buying more!) and never touching investments again.

If you’re like me and cannot care less what the stock market does because you know it’s going up in the long term then investing may be the best way to go, given the ultra-low interest rates. In fact, you should not watch the ups and downs that happen every day in the stock market. This saves the human error of wanting to “Get in and fix things” which usually ends up badly. Why? Because of our flawed human psychology, fund costs when selling/buying, capital gains taxes, and commissions. More about that on another article.

So, if you have a good savings rate and are comfortable enough with covering your mortgage in a financial downturn then going for option #2 is better.

This is why this question depends entirely on one’s circumstances. It’s not a black or white answer.

What about those taxes?

calculator mortgageThe £8,051 profit from investments may not be tax-free. If you invest those in a tax-free wrapper like a UK Stocks & Shares ISA then yes, they are. But there’s only a certain limit up to which you can invest in these wrappers. As of April 2017, this will be £20,000 per year for each person.

Usually, people having a surplus may need to pay tax on the gains (Capital Gains tax plus some Dividends tax). Therefore, if you have hit the annual allowance of £11,100 (because you’ve sold other assets like your car) you’ll pay tax on top of that.

The £8,051 will be cut to £6,822 for someone with total income up to £32,000  (18% CGT tax), and if the job income plus gains exceed £32,000 then it can go as low as £6,289! Luckily, there is a £5,000 dividends allowance before we pay tax there too.

That’s something worth considering, given that the debt you can save from paying off your mortgage is tax-free!

So maybe you want to fill-up those tax-free ISAs with investments and then contribute the rest towards your mortgage repayments.

Are interest rates going up?

If interest rates have an upwards trend then you know that you will be gaining more if you pay down your mortgage. This is simply because your debt will become more expensive overall.

Skeptical readers should really challenge me here. Who knows where interest rates are heading? Trying to predict this is like trying to predict the stock market, which we already agreed is a very expensive hobby to have.

But if interest rates are high enough, for example at 6%, then paying down the mortgage may relief some pressure.

Are you contributing to the basics?

Every person should have a pension and an emergency fund.

Are you contributing to a pension? If not then the surplus cash is actually more than £20,000 if you use it towards pension contributions. That’s because you pay less tax if you contribute more to your pension. How cool is that. Pension contributions are a great tax incentive and it makes sense to contribute there if you aren’t already.

The other basic need is to have an emergency fund for… you know… emergencies. I’m keeping a 3-month salary in a current account because if my house catches fire, I lose my job or something – touch wood – I want to be able to live off of savings until things become stable again. If you’re living paycheck-to-paycheck, stop buying lattes and accumulate an emergency fund first.


Never be afraid – action beats inaction every single time. This is what I tell myself whenever I get stressed about something. Then when I take action and even when it’s not a perfect one, I always feel better. So choose a path and take action!

Mortgage overpayments seem to be the safest option but not necessarily the one that pays better. Knowing myself, I’d put the money to work hard for me by investing as long as the interest rates are low. But although investments come with higher returns at the moment, they have their short-term bumps.

Everyone’s situation is different. What about yours?

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    13 thoughts on “Should I pay down my mortgage or invest?”

    1. This is exactly the kind of headache I have on a daily basis. Thanks for another fine article!
      I have posted it on. It’s so good I have posted it on my Facebook profile

    2. Wow, thanks Alex! Receiving these words from a field expert is very motivating 🙂

      Investing vs mortgage overpayments will always be a debate… And I believe there IS a correct answer for each one of us based on our personal situation. Thanks for sharing!

    3. I’m buying my first property and I’m struggling over this EXACT scenario. I understand in controlled terms, more money can certainly be made. However, to me it becomes more cloudy over long-term phases and multiple remortgages.

      For example I’m getting a mortgage of 105k. This is 75% LTV. My interest rate is 1.74% for a two year fix, I’ve stretched my payment period to 37years, despite being able to afford an aggressive payment period. My thinking is that inflation will eat at it? Or am I being stupid?

      My concern is what happens when rates go up as they inevitably will sometime in a 37year period. So although your example is clearcut, I wonder how this plays out over a much longer period, when clearly it will be more beneficial at certain times to aggressively pay off the mortgage? Is there a way to try this out? Or is it really possible to think in mathematical terms of each mortgage period as an isolated block and as long as you profit, you will be fine?



      • Great question Nick, and your concerns are certainly valid. But don’t get confused about the extra-lengthy term mortgage term or any remortgages. The answer is the same.

        In PURE mathematical terms, you should overpay your mortgage only if you cannot make more than the agreed interest rate (currently 1.74%) by investing elsewhere. Otherwise, you’re better off investing somewhere else and keep paying the standard mortgage payments every month.

        When interest rates rise in the next 37 years, you can start paying down the mortgage aggressively. Plus as you get older, you may not want to have a huge debt upon you. Also, since you mentioned inflation, yes inflation will eat it but stock investments are equally an inflation hedge. Bear in mind though, that stocks are highly volatile and you may lose money in the short-mid term. Paying the mortgage is always a 1.74% safe win 🙂

        It’s also worth considering taking products without overpayment fees. For example, if interest rates rise to 6% and you want to pay down £100k you don’t want to get charged extra – although admittedly I’m not sure if that’s possible. On the other hand, interest rates don’t rise 5% in a month, so you’re somehow protected against that.

    4. Would you advise using such long terms? Or much better to keep it standard and really only consider the interest payments vs saving rates?

      Regarding big overpayment, I think this is possible if you reach the end of your mortgage period and go on the SVR, I think then you’re outside penalties so could dump as much as you want in.

      I must admit I’m still unclear on the matter and would love to read more about it or see some more complex examples given with the math behind them. Do you have any suggestions on where I can find this? The time I have to change my mortgage is drastically reducing!

      • Hi Nick,
        There are definintely some factors surrounding timing which you have identified that warrant some consideration.
        If you are repeatedly doing fixed rate mortgages it becomes much more straighforward. ie.
        Y1-2 “surplus borrowing” payable at 1.74%
        End of year 2 look at the rate you can get for your next fixed mortgage for.
        -let’s say a 2 year fix is now 1.9% -you might decide to keep on investing surplus
        -let’s say a 2 year fix is now 4.0% -you might decide to sell some investments pay a chunk off your mortgage. (do it the day after your 2 year fix ends and then start a new fixed prodcut the following day to avoid all ERCs)
        In the latter example that means you need to have made a better net return on you investments over a 2 year time span than 1.74% else you would have been better to pay down your mortgage in the first place. Thus the shorter the fixed mortgage term the higher the risk of the investments underperforming. You might end up in with an uncomforable decision in the latter case if say your investments were down 10% ie do you take the pain of realising the loss or the the risky strategy of askiing your investments to recover from the loss AND best 4% net.

        You might find your investments are 20% up 18 months in – should you sell them to immeadiately to secure the gain?

        Hopefully you get the idea that this strategy requires almost constant review and decision making and while people could post illustrations they will just be examples that won’t refllct how things pan out for you.

    5. I do like investing, especially when you have things together you are still paying your mortgage and can pay extra money when your finances look healthy. Besides Im hoping the investments will help me todo both.

    6. Great article, and something I have been thinking about as I struggle to get my savings rate up. My query, well general musing, is paying off the mortgage early will reduce my monthly expenses and therefore bring forward my FI date. In addition, it will get me access to better interest rates as my LTV improves.

      I appreciate that this is an emotional justification rather than based on pure mathematics but it seems to work for me.

      • This is a sound decision, AA. They say try to reduce all your fixed expenses when you’re in FI and mortgage is a huge part of that. Being in debt also carries some risk.

        The way I see it before FI: Instead of investing in bonds which yield ~2%, put this amount in overpayments. If you have a, say 2% interest on your mortgage, it’s as if you “earn” 2% if you overpay, without having to take any risks associated with bonds! I still contemplate the idea but should take action and actually do that.

    7. Hi Michael,

      Great article, really enjoyed reading it.

      I have a similar figure to invest and will probably split it between a Stocks and Shares ISA for a least 5 years (Too risky for me to go ‘all in’ as I might need to take the money out on a downturn) and paying down my mortgage (I know interest rates are low now, but it’s a major goal of mine to pay off the mortgage – until my wife decides she wants a bigger house then I’m back to square one!).

      • Hi Rob, splitting it between S&S ISA and a mortgage is sometimes the best decision because you have no regrets whatever happens later 🙂 Good luck with your plan and pls stay in touch.


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