Shared devices on rewards sites: the owner or the multi-accounter?
Several accounts on one phone or one browser is the most common way a rewards site loses money: one person collects the welcome bonus, the referral reward and the daily offers again and again. So every fraud tool flags shared devices, and flags every account on them the same way. The data says that is half right. The accounts that arrive on a device later are the multi-accounters; the person who had the device first usually is not.
Short answer
Look at the order. The account that had a device to itself for a day or more before any other account appeared on it is its owner: give the shared device little weight there. The accounts that arrived later carry the full weight. A second account created on the same day as the first is a farm making accounts: both get the full weight.
- The owner
- Alone on the device for a day or more before anyone else: 6% of conversions reversed.
- The accounts that came later
- 75% of their conversions reversed on the same site.
- The site average
- 37% of conversions reversed by the survey networks.
- A second account the same day
- A farm, not a borrowed phone: 83% reversed.
Why a shared device is the strongest multi-account sign
IP addresses are shared by thousands of strangers behind mobile carriers and office networks, and an email address costs nothing. A device is different: a browser ID stored on the phone, or a fingerprint of its hardware and settings, follows one physical object. When five accounts log in from the same browser, one person is usually typing.
That is why a shared device weighs a lot in every fraud engine, CashoutGuard included: 55 for one other account on the same browser, 70 for two or three, 85 for four or more. A match on the hardware fingerprint alone, without the browser ID, counts much less, because identical phone models look alike (the multi-account guide explains the difference).
The problem is who gets that weight. A shared device is a fact about the device, and every account on it receives the same flag, whether it created the other accounts or had its phone borrowed by them.
Read the order and the gap
For each account on a shared device, two questions settle most cases: did this account have the device before the others, and how long was it alone on it?
- First, and alone for a day or more: the owner. Someone else came to their phone later. The shared device says little about them.
- Arrived after another account: the newcomer. This is the account that should carry the flag.
- First, but the next account came within hours: not an owner. Farms and multi-accounters create their accounts in one session, and the first of them is just the first one they made.
The gap matters because people do not lend their phone the day they sign up. A day is a short threshold on purpose: it already separates almost every farm from almost every household.
When you review a shared device by hand, open the oldest account first. If it has weeks of ordinary activity before the others appeared, look at what the newcomers do with their rewards: a newcomer that cashes out to the payout address of the owner, or that the owner referred for a bonus, makes the owner the one who benefits, and then both deserve the block.
What the data says
We looked at 30 days of a survey rewards site that reports its reversals back to us, taking every account flagged for a shared device and splitting them by their place on the device. Survey networks reverse the conversions they find fraudulent, so the share reversed is a fair measure of who really was.
| Accounts on a shared device | Accounts | Conversions | Reversed |
|---|---|---|---|
| First on the device, alone for a day or more | 22 | 249 | 6% |
| First, the next account the same day | 16 | 40 | 75% (83% with one other account) |
| Arrived after another account | 173 | 165 | 75% |
| All accounts on the site | 37% |
The owners were far less likely to be reversed than an average account on the site, yet 19 of the 22 were flagged, some of them blocked. On the same site, 8 of the 10 accounts the operator marked as legitimate in ten days had been flagged for a shared device.
How CashoutGuard does it
On every event of an account on a shared device, CashoutGuard checks when the other accounts on that device were first seen. If this account was first seen a day or more before any of them, the reason device_shared_with_accounts weighs 20 instead of 55 to 85, and shows "first on this device" with the number of days it was alone. Every account that came after keeps the full weight, and so does a first account whose next one came the same day.
- It still counts: 20 adds to the rest of the evidence on the owner, such as a VPN, an emulator or a shared payout address. It just does not flag them on its own.
- Your own weight stays yours: if you set a custom weight for shared devices in Rules & lists, that weight applies to every account on the device.
- Past events follow: flags raised on owners before the change are lowered too, without any email to your users.
The account page explains the reason in plain words, so whoever reviews it sees why the owner scores less than the newcomers. New sites start in shadow mode, so you can see who would be flagged before anything is blocked.