Every investor has a plan in a calm market. The test comes when a position is down 30%, a friend is getting rich on something you do not own, or a headline says this time is different. Decisions made in those moments are the expensive ones, and they are made with the worst information: fear, envy and a news feed.

An Investment Policy Statement (IPS) is the fix professionals use. It is a short written document that says what the money is for, how it will be invested, when it will be changed, and what you will do when markets move. Pension funds and endowments have used them for decades. CFA Institute describes the IPS as "a policy guide that can offer an objective course of action to be followed during periods of market disruption when emotional or instinctive responses might otherwise motivate less prudent actions."

You do not need an adviser or a trust to benefit from one. This post covers the sections of a personal IPS, how to fill each one, rebalancing rules with evidence behind them, if-then rules for bad markets, a one-page template, and a small script that checks a portfolio against its own policy.

Educational content, not financial advice.

1. Why write it down

The cost of improvising is measurable. Morningstar's annual "Mind the Gap" study compares the returns funds produce with the returns their investors actually earn, after the timing of purchases and sales.

Finding (10 years to December 31, 2024) Number What it suggests
Aggregate total return of US mutual funds and ETFs 8.2% per year What a buy-and-hold investor would have earned
Return of the average invested dollar 7.0% per year What investors earned after their own timing
Gap About 1.2 percentage points per year Roughly 15% of the funds' total return lost to timing
Allocation funds 6.3% investor return vs. 6.5% total return (nearly 97% captured) Automated, all-in-one portfolios leave less room for bad timing
Funds with the most stable cash flows Gap of 0.8 points per year, 1 point narrower than for funds with the most volatile cash flows The more investors traded, the less they made

The gap is an average across millions of investors and many reasons, not proof that any one rule fixes it. But the pattern is consistent across editions of the study: investors lose most where they act most, and keep most where decisions are made in advance and automated.

An IPS works on that mechanism. It moves decisions from the moment of stress to a calm afternoon. It is also an example of what psychologists call implementation intentions: plans in an "if X happens, then I will do Y" format. A large meta-analysis by Gollwitzer and Sheeran (2006) found that if-then plans help people follow through on their goals compared with goals alone. An IPS is a set of such plans for your money.

2. The anatomy of an IPS

CFA Institute's Elements of an Investment Policy Statement for Individual Investors (2010) organizes an IPS into four parts. For a personal portfolio, they map to simple questions:

Section Question it answers Personal version
Scope and purpose Which money, for whom, and why? List the accounts covered and what they are for. Exclude the emergency fund and money you need soon.
Governance Who decides, and how does the policy change? You (and a partner, if shared). A rule for how and when the IPS itself may be edited.
Objectives and constraints What return is needed, what risk is acceptable, what limits apply? Goals with amounts and dates, risk tolerance in numbers, liquidity, time horizon, taxes, personal restrictions.
Risk management How is it measured, reported and rebalanced? Target allocation with ranges, rebalancing rule, review calendar, what to track.

The paper is explicit that an IPS should be tailored: "Templates that purport to offer convenience and ease in development of an IPS almost inevitably sacrifice consideration of factors that are highly relevant to the investor." Use the template below as a checklist, not as an answer.

3. Objectives: from goals to a required return

Start with what the money is for, not with what to buy.

Term Meaning Why it matters
Goal A named use with an amount and a date: "retirement income from age 60", "house deposit in 2029" Different goals can need different portfolios.
Time horizon Years until the money is needed, and over how long it will be spent The main driver of how much volatility you can live with.
Required return The return needed to reach the goal, after fees, inflation and taxes If it is unrealistic, change savings or the goal, not the risk.
Risk capacity How large a loss you can afford without missing a goal Objective: depends on income stability, savings rate, horizon.
Risk tolerance How large a loss you can live with without abandoning the plan Subjective: what you will actually do at minus 30%.
Liquidity need Cash you may need at short notice Money needed within a few years should not depend on equity markets.

A worked example of required return, in the spirit of the CFA paper's examples: if you need the portfolio to grow 3% per year in real terms, expect inflation around 2.5% and pay 0.3% in fees, the nominal return needed before taxes is roughly 5.8%. Write the arithmetic into the IPS. When the required return is far above what a reasonable allocation can be expected to deliver, the honest fixes are to save more, extend the date or lower the target.

Risk tolerance in numbers. "Moderate" means nothing in a crash. Write it as a loss you have accepted in advance:

  • "I accept a decline of up to 25% in this portfolio without changing the allocation."
  • "In money terms, at today's value that is a loss of about 50,000. I have imagined seeing that number."

If the honest answer is smaller than the loss your allocation could plausibly produce, the allocation is wrong for you, however good it looks on paper. Risk capacity sets the ceiling; risk tolerance is often the binding limit.

4. Constraints

Constraints are the rules that apply regardless of returns. The CFA paper lists liquidity, time horizon, taxes, legal and regulatory limits, and unique circumstances.

Constraint Questions to answer Example IPS wording
Liquidity What could you need soon, and from where? "Six months of expenses are held in cash outside this portfolio and are not covered by this IPS."
Time horizon When do withdrawals start, and how long do they last? "No withdrawals planned for 15 years. Glide path review at 10 years before the goal date."
Taxes Which accounts are tax-advantaged? Where are gains realized? "Rebalance with new contributions and inside tax-advantaged accounts first, then by selling in taxable accounts."
Legal and employer Lock-ups, insider rules, vesting, plan restrictions "Employer shares are sold within 90 days of vesting, subject to trading windows."
Unique circumstances Concentrated positions, ethical exclusions, family obligations "No single company above 5% of the portfolio, including employer stock."

Concentration deserves a line of its own. A job, a bonus and a large share position in the same company are one risk, not three.

5. Asset allocation: targets and ranges

The allocation is the core of the policy. Vanguard's rebalancing research starts from the same premise: "asset allocation is the major determinant of a portfolio's risk-and-return characteristics." Write it as targets with ranges, not as a list of products.

An illustrative allocation (not a recommendation) for a long-horizon portfolio:

Asset class Target Range Role
Global equities 70% 65-75% Long-term growth
Investment-grade bonds 25% 20-30% Dampens drawdowns, source of rebalancing
Cash 5% 2-8% Near-term spending, dry powder for rebalancing

Rules worth writing next to the table:

  • Asset classes, not tickers. Funds get replaced; list the current vehicles in an appendix.
  • Fees and diversification limits. "Funds used must cost no more than 0.30% per year" is a simple, checkable rule.
  • An allowance for ideas, if you want one. If you like picking stocks or trying strategies, cap it: "Up to 5% of the portfolio may be invested at my discretion. Losses there do not change the rest of the policy." This contains the urge without pretending it does not exist.
  • What is out of bounds. "No leverage, no options except covered calls, no products I cannot explain in two sentences."

6. Rebalancing rules

Without rebalancing, a portfolio drifts toward whatever has performed best, and its risk drifts with it. Vanguard's study Best practices for portfolio rebalancing (Jaconetti, Kinniry and Zilbering, 2010) tested calendar and threshold rules on stock and bond portfolios over long history.

Finding Detail
No optimal rule "There is no optimal frequency or threshold when selecting a rebalancing strategy."
Frequency barely changes risk-adjusted return Monthly, quarterly and annual rebalancing produced risk-adjusted returns that were not meaningfully different.
But it changes costs Monthly rebalancing with no threshold required 1,008 rebalancing events; annual with a 10% threshold, only 15.
A reasonable default Annual or semiannual monitoring, with rebalancing at 5% thresholds, is "likely to produce a reasonable balance between risk control and cost minimization for most investors."
With taxes or high costs Annual rebalancing is likely to be preferred.

The three families of rules:

Rule How it works Pros Cons
Calendar Rebalance to target on a fixed date (for example, every January) Simple, predictable, easy to automate Ignores large moves between dates
Threshold Rebalance when an asset class leaves its range Responds to big moves only Needs monitoring; can trigger at stressful moments
Hybrid Check on a schedule, act only if outside the range Low effort, low turnover Slightly more complex to state

How to rebalance matters as much as when:

  1. Use cash flows first. Direct new contributions, dividends and withdrawals to the underweight asset class. Often this is enough and no sale is needed.
  2. Trade inside tax-advantaged accounts next, where there is usually no tax on gains.
  3. Sell in taxable accounts last, and only the amount needed to return to the edge of the range or to target. Write down which you choose.

Write the rule so that it cannot be argued with on the day: "On the first business day of January and July, compare each asset class to its range. If any is outside, rebalance all asset classes to target using contributions first. Otherwise, do nothing."

7. If-then rules for bad (and good) markets

This is the section you will read most, usually at night. Write it as if-then statements, in advance.

If... Then...
The portfolio falls 20% from its peak I re-read this IPS. I do not sell. I check whether equities are below their range and rebalance into them if they are.
I feel the urge to sell everything I wait 7 days and write down the reason. If the reason is a change in my goals, income or horizon, I update the IPS first, then act. If it is a headline, I do nothing.
An asset or theme rises sharply and I do not own it I can use the discretionary allowance (section 5). I do not change the core allocation.
A position grows above the concentration limit I trim it back to the limit at the next review, regardless of how well it is doing.
I lose my job or income drops Spending comes from the cash reserve first. Contributions pause. The allocation is reviewed only if the horizon or goals change.

Two principles keep these rules honest: change the policy only for changes in your life, not in the market (a new goal, an inheritance or a shorter horizon are valid reasons; a falling price is not), and add a cooling-off period to any change, for example 30 days and a second reader.

8. A one-page template

Keep the IPS short enough to read in five minutes. A plain text file is fine; structured text makes it easy to check with a script.

# Investment Policy Statement - personal
version: 3
adopted: 2026-01-28
next_review: 2027-01-15

scope:
  accounts: [brokerage-taxable, retirement-account, pension-plan]
  excluded: [emergency-fund, house-deposit-savings]
  purpose: "Retirement income from age 60; secondary: support children's education."

governance:
  decision_maker: "me, with my partner for any change to targets"
  change_rule: "Edits take effect 30 days after being written down and discussed."

objectives:
  required_real_return: 0.03
  assumptions: {inflation: 0.025, fees: 0.003}
  max_accepted_drawdown: 0.25

constraints:
  liquidity: "6 months of expenses in cash outside this portfolio"
  horizon_years: 22
  taxes: "Rebalance in tax-advantaged accounts first"
  single_company_max: 0.05
  max_fund_fee: 0.0030
  forbidden: [leverage, short-selling, products-i-cannot-explain]

allocation:            # target, min, max
  global_equity: [0.70, 0.65, 0.75]
  bonds:         [0.25, 0.20, 0.30]
  cash:          [0.05, 0.02, 0.08]
discretionary_max: 0.05

rebalancing:
  check: ["first business day of January", "first business day of July"]
  rule: "If any class is outside its range, rebalance all to target; contributions first."

if_then:
  - "Drawdown >= 20%: re-read IPS, no selling, rebalance into equities if below range."
  - "Urge to sell: wait 7 days, write down the reason, change IPS only for life changes."

9. Check the portfolio against the policy

A policy you can test is a policy you will follow. This script reads current values and reports drift against the ranges, plus what to do with the next contribution. It uses only the Python standard library.

from dataclasses import dataclass


@dataclass
class Band:
    target: float
    lo: float
    hi: float


POLICY = {
    "global_equity": Band(0.70, 0.65, 0.75),
    "bonds": Band(0.25, 0.20, 0.30),
    "cash": Band(0.05, 0.02, 0.08),
}

# Current market values per asset class, summed across all accounts in scope
holdings = {"global_equity": 162_000, "bonds": 41_000, "cash": 9_000}
next_contribution = 2_000


def check(holdings: dict[str, float], policy: dict[str, Band]) -> bool:
    total = sum(holdings.values())
    breach = False
    print(f"{'class':<14}{'weight':>8}{'target':>8}{'range':>13}  status")
    for name, band in policy.items():
        w = holdings.get(name, 0) / total
        status = "ok"
        if not band.lo <= w <= band.hi:
            status, breach = "OUT OF RANGE", True
        print(f"{name:<14}{w:>8.1%}{band.target:>8.0%}{band.lo:>7.0%}-{band.hi:<5.0%}  {status}")
    return breach


def route_contribution(holdings: dict[str, float], policy: dict[str, Band], amount: float) -> str:
    """Send new money to the class furthest below target."""
    total = sum(holdings.values()) + amount
    gaps = {n: b.target * total - holdings.get(n, 0) for n, b in policy.items()}
    return max(gaps, key=gaps.get)


if check(holdings, POLICY):
    print("\nAction: rebalance to target per the IPS rule (contributions first).")
else:
    print("\nAction: none. Inside all ranges.")
print(f"Next contribution of {next_contribution:,} goes to: {route_contribution(holdings, POLICY, next_contribution)}")

With these numbers, equities are at about 76.4% (above the 75% ceiling) and bonds at about 19.3% (below the 20% floor), so the script reports a breach and routes the next contribution to bonds. Run it on your review dates, not every day. Checking more often than the policy requires only creates opportunities to break it.

10. Review and common mistakes

Review the IPS on a calendar (annually is the common choice, and the CFA paper's examples use "no less frequently than annually") and after any major life event. Record each version with its date and the reason for the change.

Mistake Why it hurts Fix
Vague risk tolerance "Moderate" offers no guidance at minus 30% State a maximum drawdown in percent and in money
Product lists instead of policy Every fund change becomes a policy change Asset classes and ranges in the body, products in an appendix
No rule for changing the rules The IPS is edited in the middle of a panic Waiting period and a second reader
Ranges too tight Constant trading, taxes and costs Bands of about 5 points around targets are a common, research-backed start
Written and forgotten A policy that is never checked is a wish Calendar reminders, the script above, a version history

Why this matters

  • Decisions made in advance are better decisions. The IPS moves the hard choices out of the moment when fear and envy are loudest.
  • Behavior costs real money. Morningstar estimates investors gave up about 1.2 percentage points per year to timing over the decade to 2024; rules and automation are how you keep more of what your funds earn.
  • Rebalancing is risk control, not return chasing. A simple hybrid rule with 5% bands captures most of the benefit at low cost.
  • Constraints protect goals. Liquidity reserves, concentration limits and a list of forbidden products prevent the losses you cannot recover from.
  • A written policy is reviewable. You can learn from version 1 when you write version 2. You cannot learn from a decision you never wrote down.

Final Thoughts

Most investing mistakes are not analysis failures. They are moments when a reasonable plan met an unreasonable market and lost. An Investment Policy Statement does not predict the market; it decides in advance how you will respond to it.

Write the first version in an afternoon. Keep it to a page, make the risk numbers concrete, and add the if-then rules you are most likely to need. Then put the next review date in your calendar, and let the document do the arguing on the days you would rather not.

Sources