Fluid Commerce · Promotions Playbook · Oct 2026

One promo engine for the cart, the subscription, and the field.

Fluid's promo engine decides who gets a deal, on what, for how long, and whether it stacks. It runs the same rules at checkout, on every subscription renewal, and in the cancel flow, and any partner app can plug its own logic into the cart. This page explains how it works, lets you build a promo and watch it price a cart, and walks through nine plays most commerce platforms can't run without custom code.

5reward types
16eligibility rules
3places it prices: cart, renewal, cancel flow
3partner hooks for custom logic
LUMEN WELLNESS
Order #10482 · Subscription order 7
Daily Greens ×1$59.00
Collagen Bites ×1$39.00
Travel Shaker (milestone gift)$15.00 $0.00
Loyalty · Gold tier 15%−$14.70
Free ground shipping−$8.95
Total$83.30
Volume credited to rep68 CV
Three promos, zero codes typed.
Tier, gift and shipping were all applied by the engine.
How it decides

Every promo answers the same six questions, in order

A promo is a reward plus a set of rules. Each time a cart changes, the engine re-runs these steps, so a deal appears the moment a shopper qualifies and drops off the moment they don't.

  1. Trigger

    A code the shopper types, an automatic promo, a discount an admin adds by hand, or one a partner app sends.

  2. Audience

    Everyone, first-time buyers, customers or reps, a named list, an uploaded CSV, chosen countries.

  3. Qualifier

    Minimum spend, minimum item count, or a commissionable-volume (CV) window with an optional ceiling.

  4. Limits

    Start and end dates, total uses, uses per customer. Caps are re-checked at payment so a code can't be oversold.

  5. Stacking

    Each promo says whether it combines with other product deals and other shipping deals.

  6. Reward

    Percent off, dollars off, a free product added automatically, free shipping, or a free enrollment pack.

The parts list

What you can build with

Native in every store's admin Subscription Pro subscription retention add-on Droplet a partner or custom app plugged into the cart
Promo Lab

Build a promo, then try to break it

Set up a promo on the left, then change the shopper and the cart. The receipt and the rule-by-rule check update the way the live checkout would.

The promo Native

The shopper

The cart

Rule check

Nine plays

Promos most platforms can't run out of the box

Each play shows the business idea, how to set it up in Fluid, and a simulator to try it. Filter by what you're trying to move.

The write-up

What this means for the business

Where Fluid is different

  • One engine runs every channel. The rules that price a cart also price each subscription renewal and the cancel flow. A loyalty tier, a save offer and a checkout code all follow the same stacking and limit logic, so there's no second promo system to keep in line.
  • Built for direct sales. Promos can key off commissionable volume, target reps or retail customers separately, give away or discount enrollment packs, and waive the enrollment fee. Generic DTC platforms have none of these.
  • Subscriptions are treated as relationships. Discounts can last one order, a set number of orders, or forever. Tenure ladders move subscribers up tiers on their own. Cancel flows match the save offer to the reason given, A/B test two flows, and enforce a cooldown so customers can't farm discounts.
  • Partners can plug in. A droplet can add its own discounts to any cart, veto a code before it's accepted, or price subscription orders. Points, weather, inventory or fraud signals can all drive promos without changing Fluid itself.
  • Volume stays fair. When a subscription price is lower, merchants can reduce the CV credited by the same percentage, so commissions match what the customer actually paid.

Safeguards that protect margin

  • Caps hold at payment. Usage limits are checked again at checkout, so a code shared in a group chat can't run past its limit across open carts. One small gap remains: two carts finishing in the same instant on the very last use can both go through.
  • Every edit is versioned. Each change to a promo creates a new version. Carts and subscriptions keep a record of which version they got, and every change is logged with who made it.
  • Shoppers are told when a code drops. If changing the email at checkout makes a code ineligible, checkout says so instead of quietly charging full price.
  • Manual discounts need a reason. When an admin adds a discount to an order, they have to note why, which keeps finance and support aligned.
  • Multi-currency. Dollar-off promos can carry a value per currency, so a "$10 off" launch in Mexico isn't a converted, odd-looking peso amount.