# Buy envelope

Source: https://docs.tightly.io/help/commitments/buy-envelope
Reviewed: 2026-09-07

## What it is

The buy envelope is the money a commitment may place in total, at cost, in dollars: the living envelope every other money figure on the commitment is read against. For a boxed season it is a pot for the window. For a rolling commitment it is a rate per fiscal month, and the position is measured over the current month, because a cumulative ceiling on a window with no end is not a constraint anybody can act on. Declare and the money line call it the Buying budget.

A commitment may declare no envelope. Its availability floor and its pace still bind; it reserves from no pool, so it can never own the same dollar as anything else, and nothing measures money against it.

## How Tightly decides it

The planner declares the envelope on Declare with a basis, and Declare opens it at Tightly's suggestion: the scope's cost of goods sold over the trailing 180 days, scaled to the declared window's length, labelled own history. Two commitments may never own the same dollar: a declaration whose scope or pools another live commitment already owns is refused, and the rule is settled at sign-off, because a pending declaration claims no pool; submit checks too, as an earlier refusal. Per-channel legs carve the header's dollars and may never sum past them; they never add.

The envelope is measured, not enforced, on every read: placed purchase order cost against the scope over the window counts as placed, drafted orders as drafted, and the delivered slice at the order's own cost as received. The ladder ties in cents: open to commit is the buy envelope less the chase reserve less what is placed, and it goes negative when placed spend eats into the reserve, because flooring it would hide the breach. It is enforced at exactly one door: confirming a purchase order out of Drafted refuses, line by line, any line its commitment cannot fund.

The weekly verdict on the envelope reads the same ladder. Placed orders costing more than the envelope is over committed, and the replenishment engine's forward need running past free to commit is short; both are urgent at once. Otherwise it is on track, and a position that could not be computed reads not measured. Watch fires when the surplus, free to commit beyond the forward need, falls to a fifth of the envelope.

## The words on the face

| Word | Where | What it means |
|---|---|---|
| Buying budget | Declare, the desk's money line | The envelope as signed |
| Envelope | All commitments | The envelope as signed, per row and summed in the head |
| Buying reserve | The money line | The reserve still held back |
| Open to commit | The money line, the book | The buy envelope less the chase reserve less what is placed; its clause says how much of it is drafted |
| Placed | The money line | Purchase order cost placed against the scope |
| Remaining to plan | The pre-season money line | The buy envelope less the buying reserve less the worked buy |
| No envelope declared | The Bench | This commitment measures no money |
| Ceiling | The band cell of The five | An envelope has no band; this is the word that says so |

On the Bench, every prospective order says which commitment it draws on and how that sits against what it can still fund, its free to commit: Within the envelope, At the limit (within a cent) or Over the envelope. Nothing on the Bench has been spent; the envelope moves when an order is placed, not when a line is staged.

## What you can do about it

Amend moves the envelope as a new version with a receipt. Release the chase moves reserve dollars into open to commit against a named winner. Where the replenishment engine wants more than is free to commit, the money line adds Recommended buy and Funding gap, so the shortfall can be counted off the line. The Bench shows what staged lines would draw before any order exists, and Close frees the envelope's dollars the moment it commits.

## Glossary line

The buy envelope is the money a commitment may place in total at cost, a pot for a boxed window and a monthly rate for a rolling one; the envelope the ladder ties to in cents.