How much should you actually
invest each month?

This is one of the most common questions we get. The honest answer: it depends on your situation. But that's not useful on its own, so here's how we think about it.

Start with what's left over, not what feels right

The biggest mistake beginners make is choosing a number that sounds sensible rather than one based on their actual finances. "£100 a month feels reasonable" is not a plan. It might be too much if it leaves you exposed with no cash buffer. It might be too little if you could comfortably afford more.

The starting point is a budget. What comes in after tax. What goes out on essentials, rent, food, bills. What's left. Then you work backwards from there.

The emergency fund first

Before you invest anything regularly, you need 3–6 months of essential expenses in accessible cash. Not invested, sitting in an easy-access savings account. That buffer is what stops a redundancy, a broken boiler, or a car repair from forcing you to sell investments at the wrong time.

We learned this directly. When the redundancy hit in February 2026, having the ISA as a backup was useful. Having an actual cash buffer was better. The cash stayed accessible and the ISA could keep working long-term.

The 50/30/20 rule (and why it's a starting point, not a rule)

You've probably heard of it. 50% of take-home pay on needs, 30% on wants, 20% on savings and investments. It's a reasonable starting point for someone on an average salary with average outgoings. It falls apart for people in expensive cities, people with debt, people on lower incomes, people with dependants.

Use it as a check: if you're investing 0%, that's worth changing. If you're investing 40% and it's causing daily anxiety, that might be too much. The 20% isn't a target, it's a rough sense check.

What actually matters more than the amount

Consistency. A £50 contribution that goes out by direct debit on the 1st of every month, without you thinking about it, beats a £200 contribution you make in some months and skip in others.

The reason is compounding. Compounding rewards time in the market above everything else. Interruptions, months where you skip, years where you pause, have a bigger long-term cost than most people realise. Small and consistent outperforms large and irregular.

Automate the habit before you optimise the amount. The number matters less than the consistency.

When to increase it

When your income goes up and your outgoings don't. When you've cleared a debt. When the emergency fund is fully stocked. Those are the natural moments to review the amount, not because you feel like you should be doing more, but because you genuinely have more to work with.