Small Percentages, Large Consequences

A fee of 0.5% a year sounds like rounding. On a £40,000 portfolio it is £200, and it barely registers. But investment costs are not a one-off charge, they are a leak that runs for as long as you hold the investment, and the money that leaks out never gets the chance to grow.

The rough rule of thumb is that every 1% of annual cost can reduce your final pot by around a fifth over 25 to 30 years. Take £50,000 growing at 6% a year. After 25 years it becomes roughly £215,000. Knock one percentage point off the growth rate and you end up nearer £170,000. Nothing about your investments changed apart from the cost, yet £45,000 walked out of the door.

The good news is that costs are one of the few things you can control with certainty. You cannot predict markets, but you can decide what you pay to be in them.

Start With the Platform, Not the Fund

Most beginners choose a fund first and a platform second, which is back to front. The platform is the account that holds everything, and its charges apply across your whole pot, so they often matter more than the fund's own costs.

Platforms structure their fees in broadly three ways: a percentage of your holdings, a flat annual charge, or a mixture. Percentage charges are kind to small pots and expensive for large ones. Flat charges work the other way round. Many percentage-based platforms also run a tiered scale, shaving the rate once you cross £100,000, £250,000 or more, so it is worth checking which band you sit in.

Look beyond the headline rate and check:

• Whether shares and funds are charged differently, as some platforms charge more for one than the other.
• Whether each account (ISA, SIPP, general investment account) carries its own charge.
• What the dealing fee is, and whether regular monthly investing is discounted or free.
• Whether there is an exit or transfer fee, which matters more than people think.
• Whether cash sitting in the account earns interest, and how much.

Someone with £15,000 invested will usually do better on a percentage platform. Someone with £150,000 in a single account may save hundreds of pounds a year on a flat-fee arrangement.

Fund Ongoing Costs: What You Actually Pay

Every fund publishes an ongoing charge figure, sometimes called the OCF or OCR. This is the annual cost of running the fund, taken from its assets before you ever see a return, which is why it is easy to ignore.

The range is wide. Simple index trackers often sit between 0.05% and 0.25%. Actively managed funds commonly run from 0.75% to 1.5%, and some add performance fees on top. There are also transaction costs inside the fund, the dealing charges it pays as it buys and sells holdings, which appear in the costs and charges disclosure rather than the headline OCF.

Cheaper is not automatically better. But if you are paying three or four times more, you should be able to say precisely why. For most beginners, a low-cost global tracker does the job well, and the fund manager's skill is not something you can reliably identify in advance.

Trading Fees and the Cost of Doing Something

Dealing charges vary from nothing at all to around £12 a trade. On their own, a few pounds is not the issue. The issue is frequency. Twelve trades a year at £10 is £120, which on a £20,000 portfolio is 0.6% of your money gone before the market has done anything.

Many platforms cut the cost of regular monthly investing, often to £1 or £2 a trade, or waive it entirely. Setting up a monthly purchase into a fund you already hold is usually the cheapest way to add money, and it has a useful side effect: it removes the temptation to time your entries, which rarely improves returns and often harms them.

Rebalancing counts too. Once a year is plenty for most people, and you can often do it by directing new contributions towards whichever part of your portfolio has fallen behind, rather than selling anything at all.

Costs That Hide in Plain Sight

Some charges never show up on the platform's fee page.

• Foreign exchange. Buying US or global shares often means converting pounds, and the spread can cost 0.5% to 1.5% each way. Some platforms offer a much cheaper rate, so compare before dealing.
• Spreads. The gap between the buying and selling price of an investment is a real cost, and it widens in less liquid markets.
• Exit and transfer fees. Leaving can cost £25 to £50 per holding. If you plan to move platforms later, this is worth knowing now.
• Cash drag. Money left uninvested for months, earning nothing, quietly reduces your returns.
• Advice fees. If you use an adviser or a managed service, expect another 0.5% to 1% or more, sometimes plus VAT. That may be money well spent, but it should be counted.

A Ten-Minute Fee Audit

Once a year, sit down with your statements and add three numbers together: your platform charge as a percentage of your pot, the weighted ongoing charge of your funds, and your dealing costs over the past twelve months. Most people are surprised by the total.

As a benchmark, a straightforward tracker portfolio held on a competitive platform can often run at under 0.5% all in. If yours is nearer 1.5%, you are handing over a meaningful slice of your future returns for very little extra.

If you do decide to move, check whether your investments can be transferred in specie, meaning without being sold. That avoids being out of the market and can spare you a capital gains tax event outside an ISA or pension. And do not trim costs so hard that you give up something valuable: the tax shelter of an ISA or SIPP is worth far more than a few basis points. Cut the fat, keep the substance, and let the compounding do its work.