> ## Documentation Index
> Fetch the complete documentation index at: https://docs.slash.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Controls and card groups

> Decide where cards spend and how much, one card or many at a time.

## Controls

`controls` limits what a card approves: a spend `limit` per period, a
`transactionLimit`, and allow or block lists of merchants, merchant categories,
merchant category codes and countries.

```json theme={null}
{
  "limit": { "amount": { "amount": 500000, "currency": "USD" }, "period": "monthly" },
  "merchantCategories": { "mode": "block", "values": ["merchant_category_2rj4l7hmrrrcv"] },
  "countries": { "mode": "allow", "values": ["US", "CA"] }
}
```

Merchant and category ids come from [`GET /v2/merchants`](/api-reference/merchants/list) and
[`GET /v2/merchant-categories`](/api-reference/merchants/categories). Controls are replaced whole: send the full
object to change them, or `null` to clear them.

A `lifetime` limit never resets. Other periods reset at the start of the next
one in `timezone`, counted from `startDate`. [`GET /v2/cards/{cardId}/utilization`](/api-reference/cards/utilization)
shows what has been spent in the current period and what is left.

## Card groups

A card group puts cards under shared controls. Its limit is spent by all of
its cards together, and both the group's and the card's own controls must
approve an authorization.

Create a group with [`POST /v2/card-groups`](/api-reference/card-groups/create), then add a card by setting
`cardGroupId` when you create it or with [`PATCH /v2/cards/{cardId}`](/api-reference/cards/update); `null`
takes it out. [`GET /v2/card-groups/{cardGroupId}/utilization`](/api-reference/card-groups/utilization) shows the
group's shared spend.

Archive a group once none of its cards are open. Archived groups keep their
history but take no new cards.


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