📅 Last updated: 8 May 2026
· 🏷 Topic: Monthly investing, lump-sum, DCA
· 🇧🇪 For: Belgian investors
Investing monthly in instalments vs investing it all in one go (lump-sum). Which strategy wins in Belgium?
The mathematical conclusion
Research (Vanguard 2012, repeated 2022) shows that lump-sum investing has historically outperformed about 66% of the time compared with monthly instalments (DCA – dollar-cost averaging), with on average ~2-3% higher returns.
Why? Markets go up over the long run. Money that is in the market earlier benefits from those returns for longer.
The psychological conclusion
DCA wins emotionally for anyone sensitive to losses. Whoever invests €30,000 in one go today and sees the market drop 25% over the next 6 months is psychologically vulnerable to panic-selling.
DCA reduces this risk by buying gradually. In a falling market, you buy at cheaper prices.
The Belgian TOB impact
Problem in Belgium: every purchase triggers TOB (stock-exchange tax).
- €200 monthly in VWCE (1.32% TOB) = 12 × €2.64 = €31.68 TOB/year.
- €2,400 in one go in VWCE = €31.68 TOB (the same).
- But: 12 × €5 transaction cost (Bolero) = €60 in transaction costs/year (vs €5 for a single purchase).
For monthly purchases at a Belgian broker: transaction costs become disproportionate.
Solutions:
– DEGIRO Core Selection: the first trade per ETF per calendar month is commission-free regardless of size (only a €1 handling fee). Subsequent trades in the same ETF the same month are commission-free only if ≥€1,000 and same direction.
– MeDirect: since August 2025, 0% brokerage fees on the entire ETF catalogue (no monthly-plan restriction).
– Or: spread your contribution quarterly or half-yearly instead of every month to keep transaction costs in proportion.
Practical conclusion for Belgians
For monthly contributions from your salary:
– Nothing other than DCA. Don’t stop and wait for “the right moment”.
– Pick a broker with commission-free ETF purchases for monthly contributions (DEGIRO Core, MeDirect plan).
For a lump-sum (inheritance, bonus, savings):
– Mathematical optimum: invest everything immediately.
– Psychological optimum: spread over 3-6 months (not 5 years — excessively slow).
– Hybrid: 50% invested immediately + 50% spread over 6 months.
What you don’t want
❌ Waiting for “a dip”. Often it doesn’t come, and when it does you find it psychologically hard to buy.
❌ Not adjusting your monthly amount. Inflation and wage growth make €200 in 2030 worth less than €200 in 2026.
❌ Stopping during a crash. Crashes are precisely the moments of better prices — panic-stopping locks in the loss.
💡 For most investors, a regular monthly contribution with a DEGIRO or MeDirect commission-free ETF or quarterly purchases at Bolero/Keytrade works to keep transaction costs in proportion.
🔗 See Dollar-cost averaging(NL) and Time in market vs market timing(NL).
2026 Belgian capital gains tax
Since 1 January 2026, Belgium applies a 10% capital gains tax on realised gains from shares, ETFs, bonds and crypto. The first €10,000 of net gains per year is exempt. Whether you invest monthly or lump-sum does not change this — the tax applies on sale, on net gains.
Sources
- Vanguard — Lump-sum vs DCA studies
- Wikifin — DCA strategy
