When a fund or share you own pays a dividend, your platform asks a small question that most people answer on autopilot: do you want the cash paid out, or reinvested? Tick reinvest and the money buys more units the moment it lands, the position grows, and the compounding machine runs without you lifting a finger. It is one of those defaults that feels so obviously correct that thinking harder about it seems like a waste of energy.
It usually is the right answer. But "usually" is doing real work in that sentence, and the cases where reinvestment quietly costs you — through dealing charges, tax-reporting headaches, or a portfolio drifting away from the shape you wanted — are common enough that the decision deserves more than a reflex tick.
DRIP and automatic reinvestment are not the same thing
First, untangle two terms that platforms use loosely. A true DRIP — a Dividend Reinvestment Plan — is run by the company's registrar, often Computershare or Equiniti in the UK, and reinvests your cash dividend into new shares of that same company, frequently at a small discount and with low or no dealing commission. An automatic reinvestment service offered by a broker like Hargreaves Lansdown, AJ Bell or interactive investor is different: it sweeps up your accumulated dividend cash and buys more of the holding, but it charges a dealing fee to do it, typically around £1.50 per reinvestment on the platforms that offer it.
That fee is the whole ballgame for small dividends. If a holding pays you £18 in dividends and the platform charges £1.50 to reinvest it, you have just handed over more than 8% of that payment in costs before a single new unit does any work. Across a portfolio of several modest holdings, all reinvesting separately, the drag adds up fast. The compounding story only holds if the cost of buying is trivial relative to the dividend.
Accumulation units sidestep the charge entirely
Here is the cleaner route most fund investors should take, and it is an unqualified recommendation: if you hold funds rather than individual shares and you want reinvestment, buy the accumulation version of the fund (the "Acc" share class) rather than the income version with auto-reinvest switched on. Accumulation units reinvest the income inside the fund automatically, with no dealing charge and no cash ever passing through your account to be re-bought. You get the compounding for free.
The catch — and there is always a catch with this stuff — is tax. Accumulation units are not a free lunch outside a tax wrapper. The reinvested income is still taxable as if it had been paid to you, even though you never saw the cash. It is called notional income, and HMRC treats it exactly like a received dividend for your annual dividend allowance, which sits at £500 for 2026/27. Investors holding Acc units in a General Investment Account are forever digging through their platform's consolidated tax certificate to find the notional dividend figure, and plenty miss it.
Inside an ISA or SIPP, the calculus changes
If your holdings sit inside a Stocks and Shares ISA or a SIPP, the tax complication evaporates. There is no dividend tax, no notional income to report, no dividend allowance to track. In that environment the only thing left to weigh is the dealing charge on broker auto-reinvestment versus the free reinvestment of accumulation units — and accumulation units still win on funds, while a registrar-run DRIP wins on individual shares.
This is precisely why the order of operations matters. Get money into the wrapper first, choose the reinvesting share class second. An investor agonising over DRIP fees in a taxable account when they have unused ISA allowance is solving the wrong problem.
The rebalancing argument for taking the cash
There is a respectable case for switching reinvestment off and taking dividends as cash, and it has nothing to do with spending the money. When dividends pile up as cash, you decide where they go — and that lets you direct them into whichever part of your portfolio has fallen below its target weight. Automatic reinvestment does the opposite: it pours money straight back into the holding that just paid out, which is often the one that has already grown largest. Over years, blind reinvestment can leave you more concentrated in your winners than you ever intended.
For a retiree drawing an income, taking the cash is simply the point of the exercise. For an accumulator with a deliberate asset allocation, periodic cash dividends become rebalancing fuel — a way to buy the laggard without selling anything and triggering a capital gain. Neither of those investors is doing anything wrong by ignoring the reinvest box.
So what should you actually do?
If you hold funds inside an ISA or SIPP and want to grow the pot, buy accumulation units and forget about it — that is the lowest-friction, lowest-cost version of compounding available to a UK retail investor. If you hold individual shares, look at whether the company offers a registrar DRIP before you let your broker charge you per reinvestment. And if you have a deliberate allocation you care about keeping, there is nothing lazy about taking dividends in cash and pointing them yourself.
The one position that does not survive scrutiny is the default many people drift into: income units in a taxable account with broker auto-reinvest ticked, paying £1.50 a time to re-buy small dividends while a notional-income figure they never look at quietly eats into a £500 allowance. That is the combination to check on your own account this week.