Lump Sum or Drip-Feed Your ISA in 2026: A 3-Step Sliding Scale
Updated September 2026 Alpesh Patel OBE explains the sliding scale he uses, and why copying anyone else’s is a mistake.
It’s one of the most common questions we get, and on Friday’s live webinar an attendee, Raaj, put it perfectly: “Alpesh do you always lump sum into the market into your ISA and SIPP as soon as its a new tax year or do you dca providing its not a bear market”
DCA is dollar cost averaging, or drip-feeding: spreading money in over several months instead of all at once. Alpesh’s answer wasn’t “always” or “never”. It was a sliding scale.
What Is Drip-feeding?
In the US it's called dollar cost averaging. In the UK it's usually called pound-cost averaging. The idea is the same: instead of investing a lump sum on one day, you split it into equal amounts and invest them at regular intervals, often monthly.
If prices fall during that time, your later instalments buy more units. If prices rise, you'll have paid more on average than if you'd invested everything on day one. Drip-feeding doesn't guarantee a better result. What it does is reduce the risk of investing everything just before a fall, and that makes it easier to stick with your plan.
Step 1: In A Bear Market, Nothing Goes In
The first test is about price, not opinion.
“If it’s a bear, bear market, I’m not gonna put anything in. Okay? So those two moving averages falling, twenty twenty-two, not putting anything in, waiting until it flattens and rises. ’Cause price is a king.”
In practice that means looking at the trend before looking at the calendar. A new tax year is not a buy signal. If the moving averages are falling, the cash waits.
Step 2: In A Market Like Now, Drip-feed Over Three or Four Months
Markets today sit near all-time highs and look a little stretched. Alpesh’s answer for that middle ground: “It’s a bit overbought, but at all-time highs, what do you do? Then I’m more than happy to dollar cost average over three, four months.”
Drip-feeding here isn’t about predicting a dip. It’s about making sure that if one comes, you haven’t committed everything the week before.
Step 3: When It’s Undervalued And Rising, Go All In
At the other end of the scale: “Let’s say I’m more risk-loving, like, say, twelve months ago, ’cause it was just, you know, undervalued and soaring, then I’m happy to go all in.”
Value and trend pointing the same way is the one time Alpesh is comfortable putting the whole amount to work at once.
How To Drip-feed Inside An ISA
Drip-feeding doesn't mean you have to miss out on this year's ISA allowance. In most stocks and shares ISAs you can:
Pay the full amount in first. Money you pay in counts towards this tax year's £20,000 allowance straight away, even before it's invested.
Hold it as cash inside the ISA. It stays inside the tax wrapper while it waits.
Invest it in stages. Many platforms let you set up a regular monthly investment, so you don't have to remember to do it.
Check your platform's dealing fees first. If every purchase costs a flat fee, lots of small trades add up. Some platforms charge less, or nothing, for regular investments. SIPPs work the same way, but remember that tax relief can take a few weeks to reach your account.
The Catch: Your Scale Isn’t His Scale
The most important part of the answer came next: “But that’s specific to me. What you mustn’t do is try and copy somebody else. It’s the worst possible thing, because what will happen is you’ll panic and get bored.”
Two investors can look at the same market and sensibly make different choices, because their time horizon, income and nerves are different. The scale is a way of thinking, not a rule to copy.
Minimise Regret, Don’t Maximise Profit
Alpesh finished by explaining the goal behind it, drawing on the behavioural economics of Nobel winners Daniel Kahneman and Richard Thaler: “You think you’re trying to profit-maximise by trying to trade in time and get a crystal ball and see in the future. You’re not trying to profit-maximise, you’re trying to regret-minimise. ’Cause by regret-minimising, you overcome the psychological problems of exiting on a panic, then forgetting to buy back.”
He then asked the audience to put their hands up if they had ever done exactly that. One attendee, William, did. He won’t be the only one.
Quick Checklist Before You Invest Your ISA Or SIPP Money
Is the trend falling (a bear market)? Wait.
Is the market high and a bit stretched? Spread it over three to four months.
Is it undervalued and rising? It can be reasonable to invest in one go.
Whichever it is: would you regret this decision more if the market fell next month, or if it rose without you? Size your approach to that answer, not to someone else’s.
Want To Work Out Where You Sit On The Scale?
Book a free call with Alpesh’s team to talk through your own portfolio: https://call.alpeshpatel.com
Frequently asked questions
Should I invest my whole ISA allowance on 6 April?
Not automatically. A new tax year gives you a new allowance, but it isn't a signal to buy. Alpesh looks at the market trend first and then decides between waiting, drip-feeding or going all in.
Is drip-feeding safer than a lump sum?
It spreads your timing risk, but it doesn't remove market risk. Your investments can still fall in value. Its main benefit is psychological: it makes it less likely you'll panic after a bad month.
Does the sliding scale apply to a SIPP?
The same thinking applies. But a SIPP is usually a longer-term investment, so your time horizon may change where you sit on the scale.
How long should I drip-feed for?
In a market like today's, Alpesh said three to four months suits him. The right length for you depends on how much you're investing and how you'd feel if prices fell partway through.
This article is for education only and is not personal financial advice. The value of investments can fall as well as rise and you may get back less than you invest.
Alpesh Patel OBE www.campaignforamillion.com
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