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Investing vs. Mortgage Overpayments: Where Should You Put Your Money?

Got some extra cash and wondering what to do with it? One of the biggest questions homeowners face is whether to put that money into their mortgage or invest it instead. Both options make sense, but figuring out which is better can be tricky. The best choice really depends on your personal goals, your financial situation, and what's happening in the market. Let’s take a look at the key variables in making this decision.


Investing vs. Mortgage Overpayments: Where Should You Put Your Money?

Understand the Pros and Cons of Paying Off Your Mortgage Early

For many people, living without the burden of a mortgage sounds appealing. Paying off your mortgage early offers undeniable benefits, especially if you value financial security. Here’s why using your lump sum to pay down your mortgage might make sense:


  1. The interest rate on your mortgage represents a guaranteed return on your money. If your mortgage rate is 4%, every pound you pay toward your mortgage saves you 4% in interest costs. Compare this to the uncertainty of investing, where returns fluctuate.

  2. Eliminating debt can feel incredibly freeing. Becoming mortgage-free provides financial security, especially as you near retirement. You eliminate one major monthly obligation.

  3. A lower mortgage balance can lead to lower monthly payments, which helps if your income is uncertain or if you plan to downsize.


And here are some drawbacks you should consider in this situation:

  1. Paying down your mortgage means you miss the chance to invest that money elsewhere for potentially higher returns. Historically, the stock market has provided average returns of 7-8% per year, which could outpace mortgage rates, especially in today’s low-interest-rate environment.

  2. Once you put money into your mortgage, it’s not easy to access. Tapping into home equity requires taking out a loan or line of credit, which can be costly and time-consuming.

  3. In some countries (not the UK), mortgage interest is tax-deductible, which reduces the cost of borrowing. By paying off your mortgage early, you might lose these tax advantages.


The Case for Investing Your Lump Sum

Investing your lump sum can potentially grow your wealth over time, especially if you have a longer time horizon and feel comfortable with some risk. Here’s why investing might be the better choice:


  1. Historically, investing in stocks, mutual funds, or ETFs has provided higher returns than mortgage interest rates, especially over the long term. By investing your lump sum, you could significantly grow your wealth.

  2. Investing benefits from compound growth. The longer your money stays invested, the more it grows exponentially. This can be a powerful wealth-building tool, especially if you have years or decades before needing the money.

  3. Investing allows you to diversify your assets across different sectors, industries, and geographies, spreading your risk. This can be a smart move if your current assets are tied heavily to real estate.


But we shouldn’t ignore potential drawbacks of investing, viz.

  1. The stock market can be unpredictable. While long-term average returns may exceed your mortgage interest rate, there are no guarantees. A market downturn could lead to significant losses if you need to access the money soon.

  2. Investing requires discipline and comfort with risk. If market swings keep you up at night, investing may not be best for your peace of mind.

  3. Unlike the guaranteed savings on mortgage interest, investments carry risk. There’s always a chance you could end up with less than you started with.


Key Takeaways

  1. Higher mortgage rate = Consider mortgage paydown

  2. Higher risk tolerance = Consider investing

  3. Longer time horizon = Investing typically wins

  4. Need for flexibility = Keep investing

  5. Peace of mind = Mortgage paydown helps


Factors to Consider When Deciding

Now that we’ve covered the pros and cons, let’s dive into the factors that will help you make the best decision for your situation.


Interest Rates Matter

One of the most critical factors is the interest rate on your mortgage versus the potential returns on your investments. If your mortgage rate is high (e.g., above 5%), paying it down may provide better value than investing. Conversely, if your mortgage rate is low (e.g., below 3%), you might benefit more by investing in assets with higher returns.


Tax Implications

Taxes can significantly impact your decision. In some cases, mortgage interest is tax-deductible, reducing the effective cost of borrowing. By paying down your mortgage, you might lose these tax deductions, which could make investing more attractive. On the other hand, investments can also be subject to taxes, such as capital gains tax on the profits you make. It’s essential to consider how taxes affect both options and how they align with your financial situation.


Your Time Horizon

If you’re planning for retirement or another major life change soon, paying down your mortgage can provide stability and peace of mind. However, if you have a long investment horizon (10+ years), investing your lump sum could lead to substantial growth thanks to compounding.


Risk Tolerance

This is crucial. If the idea of your investments losing value keeps you up at night, paying down your mortgage might be better. If you’re comfortable with market fluctuations and understand the long-term nature of investing, it could be more lucrative.


Your Financial Goals

Are you more focused on reducing debt or growing wealth? If being debt-free is a top priority, paying off your mortgage early aligns with your goals. If you’re focused on increasing your net worth and can handle some risk, investing might be more appropriate.


Investing vs. Mortgage Overpayments: An Example

Let’s use an example to cement these concepts. Imagine you have a mortgage balance of $200k with an interest rate of 4.5% and over a term of 25 years. You have an extra $500 each month and are now wondering whether to overpay your mortgage each month or invest. You can see in the calculator below that an investment with a return of 8% outperforms the mortgage savings. 



However, this is only if that investment isn’t taxed. If the investment is taxed 10% at the end of its term then it would be better to pay that money into the mortgage. You can experiment with various scenarios using the calculator here. You should also bear in mind the non-monetary benefits and drawbacks outlined above!


A Balanced Approach: The Best of Both Worlds?

If you’re torn between the two options you can always choose a middle ground. Split your lump sum—use part to pay down your mortgage and invest the rest. This way, you reduce debt while still enjoying the potential benefits of investment growth.


For example, if you have £20,000, use £10,000 to reduce your mortgage balance and invest the other £10,000. This balanced strategy lets you benefit from both debt reduction and wealth growth.


Making the Right Choice for You

The choice between investing and paying off your mortgage ultimately depends on your personal financial situation, goals, and risk tolerance. There’s no one-size-fits-all answer. Consider the factors we’ve discussed (and our decision chart below), and if you’re still unsure, consult a financial advisor who can provide guidance tailored to your circumstances.




The good news is that whether you choose to invest your lump sum or pay down your mortgage, you’re making a proactive decision to improve your financial future. Either way, you’re taking steps to enhance your financial well-being—whether through reducing debt or building wealth.



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