The one page to write before your first contribution

This works through a written investment plan in the order the parts actually depend on each other.

What the page contains

The goal and roughly when the money is needed, what you hold and in what proportions, how much goes in and how often, and what you will do in a fall. Four short paragraphs is enough; a longer document does not get reread, which defeats the purpose.

Add the date, because a plan you can see is two years old prompts a different question from one with no date at all. Nothing on it is a forecast, and it should contain no expected return.

Why writing changes anything

A decision held in your head can be quietly revised without you noticing that a revision occurred. On paper, changing your mind becomes a visible act that has to be justified against your own earlier reasoning.

Commitment devices of this kind are used precisely because judgement in the moment is known to be unreliable. The strength of the technique is not the paper but the friction it adds to reversing course.

The fall clause is the important one

State plainly what you will do if the portfolio drops by a third: typically continue contributing, rebalance to target and change nothing else. Write the reasoning as well as the instruction, because during a decline the instruction alone reads as stubbornness. Falls of that scale have occurred repeatedly across market history and there is no version of holding equities that avoids them.

A clause you know you would not honour is worth replacing now with a lower-risk allocation you would.

Sell criteria, decided in advance

List the specific circumstances that would justify selling a holding: a change of mandate, a material rise in charges, or the money being needed. Poor recent performance is deliberately not on that list, and having written it down makes that harder to forget. Without pre-set criteria, reasons to sell get constructed after the urge arrives and always sound convincing.

The list also tells you what to ignore, which is most of what you will read.

Review rules, not review moods

Fix a date once a year and state what may be changed at it: contribution amount, allocation if your horizon has genuinely shifted, and provider if costs have drifted. Everything outside that window is left alone by default rather than by willpower. A plan with no scheduled review either never changes when it should or changes constantly.

Life events are the legitimate exception and are worth naming explicitly as triggers.

If that does not fit your week, it is not a failure of willpower.

Its limits

The page is a description of your own intentions, not financial advice, and it cannot account for tax rules that differ by country and change over time. For anything specific to your circumstances, a regulated adviser where you live is the right place to test it.

For most people, it also cannot make an unsuitable allocation suitable; it only makes an unsuitable one obvious sooner. That is still the highest-value hour available to most new investors.

The takeaway

Write it for the person who will read it in the middle of a crash, because that is who it is for.

The version you keep doing is the version that works.