Use subtotals as variablesBudgetingYou can insert a subtotal and use it as the base of a later calculation.1. Insert oneIn the markups area, use **Subtotal**. It shows the running total at the point where you place it.Drag it to reposition; a subtotal re-anchors to the category above where you drop it, and the running totals re-derive.2. Name it for what it containsThe name becomes the variable name, so it should say what is in the sum — *AfterHandlingFee* rather than *Subtotal 2*. A positional name stops being true the moment something is inserted above it.3. Use it in a calculationEvery subtotal appears in the **Subtotals** group of the Variables dialog, alongside NPC, GT and DFFF, and can be used as a markup base or in any formula:| Base | % | | ------------------ | - | | `AfterHandlingFee` | 5 |Why this is the layering mechanismMarkups are calculated in order, and some must include earlier ones. The grand total cannot express that — it includes everything, including the markup being calculated, so it is refused in budget expressions entirely.A subtotal is a **fixed point in that order**. It contains what precedes it and nothing after, so a calculation based on it is well defined. That is the whole reason subtotals are variables rather than display rows.**What they are also good for.** A subtotal is the figure a reader needs part way down — total before markups, total above the line. Even where nothing calculates on it, it earns its place by making a long budget readable.Markdown