How Referral Codes Work and How to Use Them Wisely - A Practical Guide to Referral Programs

A referral code is a unique string of characters issued so that an existing user can invite a new user to a service. The terminology varies - "invitation code," "referral code," "promo code" - but the underlying mechanism is the same. When a new user enters the code during sign-up, both the referrer and the new user receive a reward.

The format differs from service to service. A random alphanumeric string of six to eight characters is the most common, though some platforms use codes based on the referrer's username or share a dedicated referral link instead. Mercari, for example, issues a six-character alphanumeric code, while Notta uses a shareable referral link. Search "ガーターベルト" on Amazon

Why would a company hand out rewards just to get users to invite their friends? The answer comes down to cost efficiency compared with traditional advertising.

Acquiring a single new user through TV commercials or online ads can cost anywhere from several hundred to several thousand yen, depending on the industry and service. With a referral program, the existing user does the recruiting, so the company only pays for the rewards given to both parties. Even if 500 yen worth of points goes to each person, the total of 1,000 yen is far cheaper than the cost of acquiring a user through paid ads.

On top of that, users who sign up through referrals tend to stick around longer. A recommendation from someone you know carries more trust than a TV spot, and the new user starts with realistic expectations. For companies, referral programs are an ideal acquisition channel: low cost and high retention.

There is another advantage. Existing users spread the word on their own, so the user base grows without extra effort from the marketing team. For payment services like PayPay in particular, having friends on the same platform makes sending money and splitting bills more convenient, which accelerates network effects.

Referral codes and coupon codes are easy to confuse, but they work differently. Knowing the distinction helps you avoid leaving rewards on the table.

A referral code is passed from person to person. It is tied to a specific existing user, and when someone uses it, the referrer also receives a reward. It can typically be used only once, at the time of registration, and cannot be entered after the account has been created.

A coupon code, on the other hand, is distributed from the company to users. It is issued as part of a campaign or promotion and provides a discount on a specific product or service. The same code can often be used by multiple users, and it comes with a set number of uses or an expiration date.

The important thing to know is that many services allow you to use both a referral code and a coupon code together. For instance, you can sign up with a referral code to earn points, then apply a first-time coupon to your purchase on top of that. Uber Eats sometimes offers a referral discount and a separate promotional code for first orders. Using both can significantly reduce the cost of your first order.

The rewards you get from referral codes vary by service. Knowing the main types makes it easier to decide which services to sign up for first.

Point rewards: You receive points that can be spent within the service. Mercari's 500-point bonus (worth 500 yen) is a classic example. Points usually come with an expiration date, so the rule of thumb is to use them as soon as possible.

Discount rewards: Your first use of the service is discounted. Uber Taxi and GO Taxi offer discount coupons for your first ride. The discount may be a fixed amount or a percentage.

Extended free trial: The free trial period for a paid service is extended. This is common with subscription services like Amazon Prime. A standard 30-day trial might be extended when you sign up through a referral code.

Service credits: You receive credits (balance) that can be used within the service. Mobility services like LUUP grant credits that can be applied toward ride fares. Credits are similar to points but are deducted directly from the charge.

Regardless of the reward type, always check the eligibility conditions and expiration date in advance. Some services require you to complete your first transaction before the reward is granted - simply registering is not enough.

Here are the key points for making sure you receive your referral rewards and get the most value from them.

1. Have the code ready before you sign up: On most services, you can only enter a referral code once, during registration. If you finish creating your account and then realize you forgot the code, it is usually too late to add it. Before you even download the app, make a note of the referral code you want to use.

2. Check the expiration date: The referral code itself may have an expiration date. The rewards you receive after entering the code - points, coupons - often have their own expiration dates as well. An expired code will not grant any reward, and rewards left unused will eventually lapse.

3. Understand that the referrer benefits too: Referral codes are designed to reward both parties. You might think "using someone's code only benefits them," but you receive an equal or even greater reward. There is no reason to hesitate.

4. Batch your sign-ups for maximum impact: When you are starting a new chapter - moving to a new city, starting a new job - you will likely be signing up for multiple services at once. Gather referral codes for food delivery, ride-hailing, and payment apps, and register for them all at the same time. The combined rewards can easily add up to several thousand yen.

5. Become a referrer yourself: Once you have signed up, share your own referral code with family and friends. You earn a reward every time someone uses it. For services like PayPay and Mercari that people use daily, having more people in your circle on the same platform makes the service more convenient for everyone.

The timing for entering a referral code varies by service, and getting it wrong means missing out on your reward. Here are the main patterns to be aware of.

Enter during the registration form: This is the most common pattern. The sign-up form includes a field labeled "referral code" or "invitation code" where you type in the code. Mercari and PayPay use this approach. You cannot add the code after registration is complete, so be careful not to overlook the field.

Sign up through a dedicated link: There is no code entry field at all. Instead, you access a special URL shared by the referrer, and the referral is automatically applied when you register through that link. Notta and some subscription services use this method. If you create an account from the regular sign-up page, the referral will not be applied, so you must register through the dedicated link.

Enter the code after registration: Less common, but some services let you apply a code from a settings screen or promo code field within the app after you have created your account. This type is more forgiving if you forget, though there is often a deadline such as "within 7 days of registration."

If you are not sure which type a service uses, check the official help page before signing up. The individual service articles on this site also explain the exact timing for each one.

Referral codes are an easy way to earn rewards, but there are a few things to keep in mind. Knowing them in advance helps you avoid trouble.

Existing users are not eligible: Referral codes are for new sign-ups only. Even if you delete your account and re-register, you will most likely not qualify for the reward. Services cross-reference phone numbers and email addresses against past registration records.

Check the reward conditions: Some services grant the reward just for registering, while others require you to complete your first transaction. Ride-hailing apps, for example, may not activate the coupon until you finish an actual ride. If you leave the condition unfulfilled, the reward may expire before you ever use it.

Campaign details change over time: The rewards and amounts offered through referral programs can change based on company policy or campaign periods. A bonus that was once 1,000 yen may have been reduced to 500 yen. Always check the latest details on the official site or in the service articles on this site.

Abuse can lead to account suspension: Some services prohibit self-referrals (creating multiple accounts to refer yourself) and mass distribution of codes to strangers. If a violation is detected, rewards may be revoked and the account may be suspended. Use referral programs within the intended guidelines.

This site features referral codes for services whose rewards we have personally verified. For detailed registration steps and reward specifics, see the individual articles for each service.

• Mercari - Earn 500 points by entering a referral code
• Uber Eats - Discount coupon for your first order
• PayPay - Points awarded via referral code
• Uber Taxi - Discount coupon for your first ride
• GO Taxi - Discount coupon for your first ride
• LUUP - Ride credits awarded
• Amazon Prime - Rewards for signing up through a referral link
• Notta - Rewards for signing up through a referral link

If you are starting fresh - moving, beginning a new job - signing up for multiple services at once is the most efficient approach. The combined rewards can easily reach several thousand yen. If there is a service you have not registered for yet, now is a great time to take advantage of a referral code.

If you want to dive deeper into point optimization and money-saving strategies, browsing related books on Amazon is a good next step. You might find practical tips for cutting everyday expenses.