Question 1

How the fees are applied

Accepted Answer

Each month the model grows your balance at the gross market return, then charges the fees the way real platforms do. Both options use the exact same engine, so any difference in the result comes purely from their fee structures. Percentage Fees: Charged on your whole balance each month, exactly how an OCF or platform fee works (a 0.5% annual fee deducts 0.5%/12 of your pot per month). Because the fee is taken from your assets, not just shaved off the return, its drag grows as your pot grows. Flat Fees: The amount you enter is charged in full every month, deducted from the balance after that month's growth. Trading Costs: Cost-per-trade × trades per month, deducted from each option's balance every month so they share that option's real growth path. Every figure shown, including each option's final value and the gap between them, reflects the true effect of trading frequency.

Question 2

What should you enter for Options A & B?

Accepted Answer

To accurately compare two platforms, your "Annual Fee" should include both the Broker Platform Fee and the Fund OCF (Ongoing Charges Figure). Example 1 (Traditional): HL Platform (0.35%) + Active Fund (0.75%) = 1.10% Annual Fee. Example 2 (Flat-Fee): Interactive Investor Core (£5.99/mo) + Vanguard Global All Cap (0.23%) = £6 Flat Fee and 0.23% Percentage Fee. (Note: You can model the fund OCF as part of the percentage slider and the platform cost as the flat amount).

Question 3

Reading the sidebar chart

Accepted Answer

The chart visualises the divergence between your choices over time: Blue Line: The growth path of Option B. Orange Line: The growth path of Option A. Red Shaded Area: The "Wealth Gap", the absolute difference in pounds between the two paths. Notice how it starts thin but widens aggressively as the years pass; this is the power of compounding working against the higher-cost option.

Question 4

What this tool doesn't model

Accepted Answer

This is a simplified illustrative model. It assumes: Constant returns & fees: Real markets are volatile, and many platforms have tiered pricing (fees falling as your pot grows) which isn't captured here. No Tax: Inside an ISA or SIPP, there is no tax. In a GIA, dividends and gains would reduce these final figures. Nominal Figures: Values are not adjusted for inflation. In real terms, the buying power of the final pot will be lower.

What are fees really costing you?

Your wealth, two fee paths

How the comparison works

Know exactly what you're actually paying.