How to stop one person from creating multiple accounts
To stop one person from creating multiple accounts, tie each reward or limited offer to something a person cannot copy as easily as an email address. Picture a platform that gives every new user a reward. Someone signs up with five email addresses and claims it five times. Every address is valid and none of the accounts is a bot, yet all five belong to one person. Email confirmation, CAPTCHAs and bot detection tell you an account works and a human is typing. They do not tell you whether this person has registered before.
Most services layer phone verification, device and network signals, payment card checks and limits per household. Those catch casual repeat claims. Phone numbers, devices and cards can all be bought or borrowed, so a determined person gets through, and a full identity check (KYC) is costly to run for every promotion.
The Trust Identity Protocol (TIP) by The AI Lab adds a verified person that works across services. A person gets a TIP-ID once, after an accredited Verification Provider checks a government ID and a live face. TIP's deduplication check refuses a second TIP-ID for a government ID that already has one, and it does so without publishing the ID number. A service that asks for a TIP-ID at a reward or payout can record it and see when the same verified person comes back under a new email address. The service never receives the person's ID documents.
The problem
Where one person with many accounts costs money
| Where | What goes wrong |
|---|---|
| Sign-up rewards and referral bonuses | One person opens several accounts with different email addresses, refers themselves and collects every reward. |
| Promotions, coupons and free trials | First-order discounts and free trials meant for new customers are claimed again and again by the same people. |
| Paid research and surveys | One participant joins the same study under several identities, so the team pays more than once and the duplicate answers skew the results. |
| Recruiting and applications | One applicant applies many times under different names or addresses, which adds review work and can game limited or ranked programs. |
| Votes, giveaways and limited drops | Anything limited to one per person, from a poll to a ticket release, can be swept by one person running many accounts. |
Every option, honestly
What each option does, and where it stops
These work together. Use more than one, and read the last column for each, including ours.
| Option | What it does | Where it stops |
|---|---|---|
| Email confirmation | Confirms the address exists and someone reads it. | Anyone can create as many addresses as they like, for free. |
| CAPTCHA and bot detection | Separates people from automated scripts. | Says nothing about whether a real person already has another account. |
| Phone verification | Ties the account to a working number. | Extra and virtual numbers are cheap and easy to get. |
| Device, network and payment signals | Flags accounts that share a device, network or card. | Shared homes cause false matches, and new devices, proxies and cards get past it. |
| Full identity check (KYC) | Confirms a real person with a government ID. | Costly to run for each promotion, and the person repeats it at every company. |
| Trust Identity Protocol (TIP) by The AI Lab | Lets a service accept a TIP-ID, issued after a government ID and live face check and a deduplication check against IDs already used, and record it with each claim so a returning person shows up across email addresses. | Does not judge behavior or stop a real person from cheating in other ways. It adds a verification step, so ask for it only where repeat claims cost real money. |
Step by step
How to put it in place, in order
- Find the points where one person claiming twice costs you money, such as a sign-up reward, a paid session, a referral payout or a limited place.
- Keep sign-up open, and ask for a TIP-ID only at those points.
- Store the TIP-ID with each claim, and refuse or review a second claim from the same TIP-ID.
- Keep your device, network and payment signals running for everything else.
- Compare what repeat claims cost before and after, and decide whether the verification step pays for itself.
- Tell people why you ask, and that a TIP-ID check never hands you their ID documents.
About TIP
What the Trust Identity Protocol is
The Trust Identity Protocol (TIP) is an open standard from The AI Lab for proving who made a piece of content and whether it has changed. A person or organization is verified once by an accredited Verification Provider and gets a TIP-ID. Each time they sign something, their own device signs it with a post-quantum signature (ML-DSA-65, NIST FIPS 204) after a fresh fingerprint or Face ID, and the TIP Network records the signature, the time, an origin label and a fingerprint of the content. Anyone can check a record for free, with no account.
TIP does not detect deepfakes, does not stop copying and does not decide whether content is true. It proves who stands behind a piece of content and whether a copy matches the original. It is governed in the open by the AI Trust Council, and the specification is public on GitHub. Signed content is called a Verifiable Asset.
Questions
Questions people ask
How do I stop users from creating multiple accounts?
Decide where a second account costs you money, and ask for proof of a unique person at that point instead of at sign-up. Phone, device and payment checks stop casual repeat claims. For valuable rewards, accept a TIP-ID from the Trust Identity Protocol (TIP) by The AI Lab, which is issued after a government ID and live face check, and record it with each claim so the same verified person cannot collect twice under new email addresses.
Why don't email and bot checks stop duplicate accounts?
They answer different questions. Email confirmation proves an address works, and a CAPTCHA or bot check suggests a human is present. Neither tells you whether that human already has an account under another address, which is the question a one-per-person reward depends on.
How do paid research teams and recruiters catch duplicate participants?
They screen for repeated devices, payment details and answer patterns, and they review suspicious entries by hand. Asking for a TIP-ID before a paid session or a limited application lets a participant prove they are a verified person without sending their ID documents to every study or employer, and a repeat TIP-ID is easy to spot.
Can TIP check whose behalf an AI agent is acting on?
Not yet. When an AI agent books a flight or makes a purchase, a service needs to know whose behalf it acts on and what it is allowed to do. TIP today issues verified personal and organization identities and keeps organization rosters signed by both the organization and each member. The AI Lab has proposed agent identities, signed delegations and action receipts on TIP, and those are not yet built. The proposal is at theailab.org/insights/public-record-of-what-ai-agents-do.
Who decides how TIP develops?
The AI Trust Council, a group of independent stewards from five constituencies (Creators, Institutions, Publishers, Operators and Partners). A matter passes when three of the five constituencies approve, so decisions about the protocol do not rest with one company. The members are listed at theailab.org/ai-trust-council/members.
When is a TIP-ID worth the extra step?
Where not knowing who is behind an account has a clear cost, such as a reward budget, a paid study or a limited place. If your fraud controls already keep repeat claims low, the extra step may not pay for itself. Ask at the moment money or a limited place changes hands, and keep everything else open.
Does a service see my ID documents if I use a TIP-ID?
No. An accredited Verification Provider checks your ID when you create your TIP-ID. A service checking your TIP-ID sees that you are a verified person, not your documents. Your face image is used once to confirm you match your ID, then deleted.
What is the Trust Identity Protocol?
The Trust Identity Protocol (TIP) is an open standard from The AI Lab for proving who made a piece of content and whether it has changed. A person or organization is verified once by an accredited Verification Provider and gets a TIP-ID. Each time they sign something, their own device signs it with a post-quantum signature, and the TIP Network records who signed it, when, how it was made (Original Human, AI-Assisted, AI-Generated or Mixed) and a fingerprint of the content. Anyone can check the record for free.
What does TIP cost an organization?
Checking any TIP record is free for everyone, with no account. Signing is free for individuals, nonprofits, schools and universities, government bodies, journalism organizations for editorial use and businesses under USD 100,000 in annual revenue. Larger businesses use a published commercial license, with every tier listed at theailab.org/tip-license.
SourcesJohn R. Douceur, The Sybil Attack, Microsoft Research, 2002, TIP Acceptable Use Policy, more than one TIP-ID, TIP Privacy Policy, face images, The AI Lab, a public record of what AI agents do, AI Trust Council members
Other use cases
Where else TIP helps
- Hiring and recruiting
- Students and academic integrity
- Certificates and credentials
- Insurance claims
- Freight and logistics
- Newsrooms and journalism
- Archives, libraries and museums
- Research publishing
- Creators and creator platforms
- Banks and finance teams
- Agencies, brands and marketing
- Referral, rewards and marketplaces
- Documents from people you have never met
- All use cases