Portfolio rebalancing calculator

See how far your mix has drifted, then buy your way back with new money before you ever think about selling. Includes a per-country sell-tax estimate.

Portfolio rebalancing calculator

The rows below are an example. Type over them with your own holdings. Figures stay in euros on this page; edit them to your own currency and numbers.

Holding name

Target %

Current value

Holding name

Target %

Current value

New money to add each month

How much drift you'll tolerate

Buy your way back

Holding name	Now	Target	Drift (percentage points)	Status

If buying back isn't enough (the last resort)

Your country (for the sell-tax estimate)

Tax rate on the gain (you can edit this)

Inside a tax-free wrapper like an ISA, SIPP or PEA? Set this to 0.

How much of the sale is profit (a rough guess)

This is a back-of-envelope estimate, not a tax return. It assumes a slice of what you sell is profit and applies your country's headline rate, both of which are yours to edit. It ignores your annual allowance, any losses, your cost basis and your holding period, so it usually overstates the bill. Rates and rules move. Check your own national tax authority before you sell, and see the country table in the guide for the rules this tool doesn't model.

This is not tax advice, and not a recommendation to buy or sell any product.

Inside a Stocks and Shares ISA or a SIPP, switching between funds is not a taxable event. In a General Investment Account, gains above the £3,000 yearly allowance are taxed at 18% (basic rate) or 24% (higher rate). Ireland taxes fund and ETF gains at 38% exit tax, with no annual exemption and an 8-year deemed-disposal clock. Directly-held shares are 33% CGT with a €1,270 yearly exemption instead. There is no ISA-equivalent. Inside a PEA held five years or more, gains escape income tax but still pay 18.6% social charges. A normal compte-titres pays the 31.4% flat tax (the social-charge part rose from 17.2% to 18.6% for 2026). Very high incomes can add a 4% surcharge. There is no tax-free switching wrapper; the Vorabpauschale already taxes fund gains yearly. Equity funds get a 30% partial exemption (Teilfreistellung), so their effective rate is lower. Church members add Kirchensteuer. A switch itself is not taxed in the Netherlands. Box 3 taxes the value of your holdings on 1 January each year (2026 tax-free capital €59,357 per person; deemed returns 1.28% on savings, 6.00% on investments). From 1 January 2028 a new Box 3 regime is due to tax your actual return. A fund-to-fund traspaso defers the tax for qualifying mutual funds; ETFs have not qualified since 1 January 2022. Savings gains are taxed on a ladder from 19% up to 30% by size. There is no ISA-equivalent. Most disposals are taxed at 26%; Italian and white-list government bonds are taxed at 12.5%. A flat 28% is the default; longer holding cuts the taxable gain (10% off after 2 years, 20% after 5, 30% after 8). Holdings under a year are taxed at your marginal rate if your income tops about €86,634. PPR retirement plans can qualify for reduced rates. Slovenia's rate falls the longer you hold: 25% under 5 years, 20% after 5, 15% after 10, 10% after 15, and 0% after 20 years. Set the rate for your own holding period. The new INR investment account (accounts from 5 March 2026) defers tax and applies 15% on withdrawal. There is no EU-level capital-gains tax; the rule is national every time. Pick your country above for a starting rate you can edit. The pan-European PEPP is the nearest cross-border wrapper.

What this calculator does

It shows you the cheapest way to fix a portfolio that has drifted off its target mix. Tell it what you hold, the mix you're after, and what you pay in each month. It works out how far each holding has drifted, whether new money alone steers you back without selling, and how long that takes in months. Selling is the last resort, shown only if buying can't get you there.

How it works

The tool restores your chosen mix with buy orders first and only sells as a last resort. It measures drift against the 5/25 rule: a holding is out of band once it moves five percentage points from its target, or a quarter of its own weight for smaller holdings, whichever is tighter. Your most-overweight holding sets the buy-only plan. The tool finds the total your portfolio must grow to for every other holding to catch up with new money, then splits your top-up across them. If a holding you want at zero is still held, buying can't dilute it away, so the tool routes you to a sale. The sell figure is the smallest one-way sale that restores your target. The per-country tax rates are editable assumptions with their sources listed in the guide; they're the headline rate on a realised gain, not the full rules, and they ignore your allowance, your losses and your cost basis. Account types are named for general information, not a recommendation to open any product.

When to use it

Reach for it once a year, or whenever a holding has run away from its target and you're not sure what to do about it. It's built for European investors, so it asks which country you're in and gives you a starting tax rate for a sale, because switching funds is tax-free inside some wrappers and taxed in others, and the rate is national every time. It's a rebalancing plan, not a recommendation to buy or sell any particular fund.

Read the full guide: how to rebalance your portfolio