Unique vs Fixed Birthday Discount Codes: Which Strategy Works Better?

TL;DR: For Shopify birthday emails, use a fixed code if you’re just starting out. Switch to unique codes when you want to prevent code sharing and track exactly which emails drive sales.

The Happy Birthday App gives you both options. Here’s how to decide which one fits your store. (New to birthday marketing? Start with our Happy Birthday App for Shopify.)

The Two Approaches

Fixed Code: One Code for Everyone

With a fixed code, you create a discount in Shopify (like “HAPPYBDAY15”) and use that same code in every birthday email. Simple and straightforward.

How it works:

• You create the discount code in your Shopify admin
• You link it to the app
• Every customer gets the same code in their birthday email

Unique Codes: A Personal Code for Each Customer

With unique codes, the app automatically creates a fresh discount code for each customer when their birthday email goes out. Something like “BDAY-SARAH-X7K2” instead of a generic code.

How it works:

• You set the discount value (like 15% off or €10 off)
• The app generates a unique code for each customer
• Each code can only be used once

When to Use a Fixed Code

A fixed code makes sense when:

• You’re just getting started – Keep it simple while you test birthday marketing
• You have a small customer base – With fewer customers, code sharing is less of a concern
• You already have a birthday discount set up – No need to change what’s working
• You want full control in Shopify – Manage usage limits and expiry dates yourself

For tips on what discount percentage or amount works best, check out Birthday Discounts That Convert.

When to Use Unique Codes

Unique codes work better when:

• You want to prevent code sharing – Customers can’t share their code on deal sites or with friends
• You want to track individual results – See exactly which birthday emails led to purchases
• You have a larger customer base – More customers means more potential for code abuse
• You want codes to expire automatically – Set codes to expire 7 days after the birthday, for example

The Code Sharing Problem

Here’s something that happens more often than you’d think: a customer receives their birthday code, posts it on social media or a coupon site, and suddenly dozens of people are using “your” birthday discount.

With a fixed code like “BIRTHDAY20”, there’s no way to stop this. Anyone who finds the code can use it.

With unique codes, each code is tied to one customer. If someone tries to share “BDAY-SARAH-X7K2”, it won’t work for anyone else. Problem solved.

What You Can Customize with Unique Codes

When you choose unique codes in the app, you can set:

• Discount type – Percentage off (like 15%) or a fixed amount (like €10)
• Minimum order – Require a minimum purchase to use the code
• Validity period – How many days the code stays active after it’s created
• Which products – Apply to everything, specific collections, or specific products

Which One Converts Better?

Honestly? Both can work well. The discount itself matters more than whether the code is unique or fixed.

That said, unique codes have one clear advantage: you can see exactly how much revenue each birthday email generates. When Sarah uses her unique code, you know that purchase came from her birthday email. With a fixed code, you’re guessing.

Our Recommendation

If you’re new to birthday marketing, start with a fixed code. It’s simpler to set up and you can always switch later.

If you’re serious about birthday marketing as a revenue channel – or if you’ve noticed your codes showing up on coupon sites – switch to unique codes. The extra tracking and fraud prevention are worth it.

Not sure how to collect birthdays in the first place? The thank you page widget is the easiest way to start – it asks customers right after they purchase, when they’re most likely to share.

And if you’re selling internationally, you’ll want to send those birthday emails in your customers’ language for better results.

Ready to try it? The Happy Birthday App includes both discount options, and you can start free with up to 50 subscribers.