Positions forced assumptions

Why can Positions and Analysis disagree on the same strategy?

Because they are reading two different versions of the same run. A backtest is computed as every combination of the three assumptions, and each view picks one: the Analysis views follow your toggles, while Positions is hard-wired to the gross, reinvesting combination. Once you turn Costs & interests or Taxes on in Analysis, that view's path through history is no longer the path Positions is showing — costs and tax withdraw money as the simulation runs, which changes the capital available at each rebalance, and therefore the weights, position counts, and cash left over. Both views are correct; they are answering the question under different assumptions.

Which assumptions does the Positions view force?

In prose: Positions gives you exactly one reading — reinvesting, gross of costs and gross of tax — and does not let you change it. That is also why the Positions view carries no assumptions toggle group at all, while the Analysis views do: the controls would have no effect there.

How does Fincanva handle it?

• The forced set matches the default state of the Analysis assumptions (Reinvest profits on, Costs & interests off, Taxes off), so out of the box the two views agree. They diverge only after you switch Costs & interests or Taxes on in Analysis.
• Positions is re-parameterized by two things instead: the rebalance date you select and the "Capital" input. Neither of those is an assumption — they change which snapshot you see and how it is scaled.
• Every Positions figure inherits the forced set: the "Target notional", "Cash", "Positions" and "Accuracy" KPIs, the "Target allocation" chart, the "Order plan" card, and the "Target positions & exits" sheet.
• The forced set applies to the Positions view only. It does not alter the saved run, your saved assumption rates, or anything the Analysis views show.

What does it look like in practice?

A strategy shows a set of target weights in Positions for the rebalance date of 1 June, and the same date appears in Analysis. With Analysis on its default assumptions the two match. You then switch Taxes on in Analysis: its figures change immediately to the after-tax version — because the tax on the gains realized since the start has been taken out of the simulated account along the way — as events occur under the Administered tax regime, once a year under Declarative — the portfolio reaching 1 June is smaller, so the money behind each weight differs and small positions can round differently. Positions does not move at all, because it never left the gross, reinvesting version. Nothing is broken and nothing needs re-running: you are looking at the same strategy under two different assumption sets, and only Analysis lets you pick which.