Q: What does it look like in practice?

A strategy is showing a gross return with Taxes off. You flip Taxes on: the displayed return, its annualized figure and the monthly numbers all drop to their after-tax values immediately, because that variant was pre-computed at the last backtest — no new backtest starts. What persists is everything you didn't touch: the backtest itself, the strategy's settings and your saved tax rates are unchanged, so flipping Taxes back off restores the gross view instantly. Editing a tax rate in Settings is the opposite kind of change — that is persisted, and the strategy must re-run before the new rate shows up. Switching an assumption changes what a past backtest is reported to have produced, not what a strategy will produce.

Question 1

How does Fincanva handle it?

Accepted Answer

They live in the bar at the bottom of every page you open for a strategy, behind the sliders button, which shows how many of the three are on (for example 2/3); it opens a panel titled Simulation assumptions. The word "Assumptions" is no longer a navigation label — this group carries the name. Costs & interests covers trading costs, financing and interest; Taxes covers tax on dividends and realized capital gains; Reinvest profits compounds realized profits. By default a backtest is shown with Costs & interests and Taxes off and Reinvest profits on — gross of costs and tax, with profits compounding. Reinvest profits also decides which annualized-return metric appears: on shows CAGR (geometric), off shows AAGR (arithmetic). The three govern the Analysis views. The Positions view ignores them and always reads the gross, fully-reinvested version, which is why the two can show different numbers.

Question 2

What does it look like in practice?

Accepted Answer

A strategy is showing a gross return with Taxes off. You flip Taxes on: the displayed return, its annualized figure and the monthly numbers all drop to their after-tax values immediately, because that variant was pre-computed at the last backtest — no new backtest starts. What persists is everything you didn't touch: the backtest itself, the strategy's settings and your saved tax rates are unchanged, so flipping Taxes back off restores the gross view instantly. Editing a tax rate in Settings is the opposite kind of change — that is persisted, and the strategy must re-run before the new rate shows up.

Switching an assumption changes what a past backtest is reported to have produced, not what a strategy will produce.

Question 3

Which changes are instant, and which need a re-run?

Accepted Answer

The three toggles and the rates behind them behave differently, which is the key to reading them: Instant — the toggles. Flipping Costs & interests, Taxes or Reinvest profits switches what you see immediately, with no new backtest. Fincanva computes every combination when the strategy runs, so a toggle just reads the matching already-computed variant. Saved — the rates. The values behind the toggles — your cost and interest assumptions, and your tax rates and regime — are saved in Settings. Changing a rate is a settings change: the strategy reads Needs re-run, and the rate takes effect only after it re-runs.