The Hidden Risks of DIY Investing
In the 1990s, programmes such as Changing Rooms and Ground Force encouraged more people to tackle their own home and garden projects.
For some, this worked brilliantly. For others, the cost of bringing in a professional to correct a mistake made the project considerably more expensive.
DIY investing can follow a similar pattern.
Managing your own investments can be simple, accessible and cost-effective. For many people, particularly those starting out, it may be entirely appropriate. Risks tend to emerge as the amount invested grows, life becomes more complicated, and financial decisions begin to overlap.
The real question is not whether DIY investing is good or bad. It is whether you have the time, knowledge and confidence to manage everything involved.
What Is DIY Investing?
DIY investing means making your own investment decisions without receiving personal financial advice.
Online platforms have made this easier than ever. Investors can open an ISA or pension, select investments and monitor their portfolio from a phone or computer.
Low-cost index funds can also provide a straightforward way to invest across a broad market. For someone with a clear goal, a long timeframe and an understanding of the risks, this may be all they need.
However, choosing an investment is only one part of managing your financial future.
Risk One: Investing Without a Financial Plan
When you are 18 and starting work, or 21 and leaving university, your immediate goal might be to move out or save for a house deposit.
The plan may be relatively simple: understand how much you need, establish a budget and save regularly. Many people can do this without a financial adviser.
Long-term financial planning is different because life rarely follows a straight line.
Consider someone who started investing in their early twenties and had accumulated more than £50,000 by the early 2000s, equivalent to considerably more today.
Then circumstances changed. Markets fell following the dotcom boom, children arrived, the family moved house, and a period of unemployment followed. By 2010, the money had gone.
The lesson is not that investing failed. It is that money without a clear purpose can easily be diverted when circumstances change.
A financial plan helps you decide:
What the money is for
When you are likely to need it
How much investment risk you can afford to take
How much should remain accessible in cash
What may need to change when life changes
Saving and investing are important, but they work best when they support a wider plan.
Risk Two: Allowing Investing to Become Exciting
Good investing is often quite boring.
It usually involves setting appropriate goals, spreading risk, controlling costs and remaining patient. It rarely involves continually chasing the next exciting opportunity.
Today, investors are surrounded by stories about fast profits. A particular technology company, cryptocurrency or investment theme can appear to offer a shortcut to financial security.
The success stories receive attention. The people who bought at the wrong time or suffered substantial losses are less visible.
Recent FCA research found that 66% of investors aged between 18 and 40 made an investment decision in less than 24 hours. Two in five later regretted buying a hyped investment. This does not mean younger people should not invest. It shows the danger of letting excitement and urgency replace careful decision-making.
The practical challenge for DIY investors is not simply choosing investments. It is continuing to make sensible decisions when markets become volatile, headlines are unsettling, or another investment appears more exciting.
Risk Three: Reacting to Market Falls
Investments do not rise in a straight line.
A diversified portfolio will still experience periods when its value falls. This can cause anxiety, particularly when the money represents years of work and saving.
The danger is that an investor sells after markets have fallen and only feels comfortable investing again once prices have recovered. This can turn a temporary fall in value into a permanent loss.
A suitable investment strategy should consider:
Your goals and investment timeframe
Your willingness to accept fluctuations
Your financial ability to withstand losses
The amount you may need to withdraw
How the investments work together
It is relatively easy to accept investment risk when markets are rising. The real test comes when they fall.
Risk Four: Overlooking Tax
You can't consider an investment separately from the tax wrapper holding it.
At a basic level:
Eligible pension contributions may receive tax relief, while withdrawals beyond any available tax-free amount are normally taxable.
ISA contributions do not receive tax relief, but withdrawals are normally free of UK Income Tax and Capital Gains Tax.
That sounds straightforward, but deciding which to use can be more complicated.
Pensions and ISAs often work well together. The right balance may depend on your income, access needs, retirement plans, tax position, and estate-planning needs.
Pension rules are also changing. From April 2027, the government intends to include most unused pension funds and pension death benefits when calculating Inheritance Tax. This makes it even more important to review pension and estate-planning decisions rather than relying on rules that applied in the past.
Tax rules depend on individual circumstances and can change. The important point is that investment selection, tax planning and financial planning should be considered together.
When Might Financial Advice Be Helpful?
You may benefit from financial advice when:
Your finances are becoming more complex
You are approaching or entering retirement
You have several pensions, ISAs or investments
You have received an inheritance
You are selling or extracting money from a business
You are worried about tax or estate planning
Market movements are causing anxiety
You no longer have the time or desire to manage everything yourself
Advice can also be valuable after a major life event, such as redundancy, divorce, bereavement or a change in health.
Bringing Everything Together
DIY investing can be the right approach.
It can help people begin investing, keep costs under control and become more engaged with their finances. Experienced investors with sufficient time and knowledge may be comfortable managing their own portfolios throughout their lives.
The problems generally arise in three areas:
No clear plan: Money is invested without a defined purpose, timeframe or contingency for changing circumstances.
Investment decisions take over: The portfolio becomes the plan, rather than one part of it.
Tax is considered too late: Decisions are made without understanding how pensions, ISAs, withdrawals and estate planning work together.
The value of financial advice is therefore not simply finding an investment. It is helping you make joined-up decisions and remain focused on the life the money is intended to support.
The Castlebay Way
At Castlebay Financial Management, we recognise that people need different levels of support.
Our three service levels are:
Transactional: One-off financial advice for a specific need, such as pension advice, inheritance planning or investing a lump sum.
Principal: Streamlined advice with an annual review, investment monitoring and the option to add further support when needed.
Strategic: In-depth, ongoing financial planning, including cash flow modelling, regular reviews and ongoing investment advice.
You do not have to hand over every financial decision or wait until you reach a particular level of wealth.
If managing everything yourself is becoming stressful, time-consuming or too complicated, we can help you understand your options and decide what support is right for you.
Important information
This article is for general information only and does not constitute financial advice. Financial planning and investment decisions should be based on your individual circumstances. Tax rules and legislation can change, and their impact will depend on your personal situation. If you would like advice tailored to your circumstances, please speak to a qualified financial planner.
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Last reviewed: September 2026
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