The NFL regular season begins Wednesday night, beginning a busy period for U.S. sports bettors.
According to a Siena Institute survey of 3,084 people conducted between February 16 and 27, 27% of Americans now have an active online sportsbook account, up from 19% in 2024. The confidence interval for the survey, conducted by a nonpartisan polling organization, is plus or minus 1.9 percentage points.
But as more people place bets online, some may take sportsbook rules lightly, unaware that violating them can affect their bets and accounts, experts told CNBC Make It.
These rules can govern where you can bet, who can bet, and even how you fund your account. And prediction markets pose further problems by offering sports contracts that look like traditional betting but follow different rules.
Here are some things experts say bettors should know.
You cannot ask someone else to bet on you.
Bill Simmons, podcaster and founder of sports and pop culture site The Ringer, is a recent high-profile example of what happens when someone else uses your sportsbook account.
On the Aug. 30 episode of “The Bill Simmons Podcast,” Simmons said she directed her daughter’s boyfriend to place bets on her behalf in Massachusetts using Simmons’ account at the online sportsbook FanDuel. Simmons lives in California, where online sports betting is not legal.
FanDuel subsequently voided the bet, took action against Simmons’ account and reported the matter to the Massachusetts Gaming Commission, a company spokesperson told CNBC Make It.
Simmons later said he “didn’t know about the agent rule” but thought the act was allowed.
“Many casual bettors don’t realize that having a spouse or friend bet on their behalf is against the rules,” said Eric Chaffee, a law professor at Case Western Reserve University who studies sports betting regulations.
Placing bets on behalf of another person, known as proxy gambling, is prohibited as it can be used to circumvent state-specific gambling rules. Violating these rules can result in account suspension and forfeiture of winnings, Chaffee says.
Sportsbooks also place restrictions on how you can fund your account. FanDuel told CNBC Make It that it monitors deposits and rejects payment methods if the name doesn’t match the account holder. The company will also suspend accounts while investigating possible fraud.
Where you are matters – “It’s not where you live”
Even if you have a sportsbook account in a state where online sports betting is legal, that doesn’t mean you can use it everywhere.
“This is about where you are, not where you live,” says Chaffee.
Sportsbooks must ensure that bettors are physically present in a jurisdiction where they are allowed to accept bets. That means you can place a bet through an app in one state and find that new bets are blocked when you cross state lines, said Ross Weingarten, a former federal prosecutor and co-chair of the sports integrity team at law firm Steptoe.
GeoComply, which provides geolocation technology to major sports betting platforms such as FanDuel, says its technology checks hundreds of signals to confirm a bettor’s location and can double-check the device during a betting session, such as when someone appears to be traveling or near state lines.
Weingarten said major sportsbooks typically allow customers to withdraw funds even in states where betting is prohibited or restricted, even if they cannot place new bets. However, if the sportsbook determines that you are attempting to circumvent state gambling regulations, the company may freeze your account and void your winnings.
VPN can interfere with location verification
VPNs are often used for work and privacy, but they can cause unexpected problems for sports bettors.
Virtual private networks (VPNs) can spoof a user’s location, so sportsbooks may not be able to see where bettors are actually located. This means that even if you are physically located in a state where online sports betting is legal, you may be blocked from placing bets while the VPN is running.
GeoComply says active VPNs are not inherently suspicious. Often, customers simply forget they have a work or personal VPN running and are told to disable it and try again.
However, repeated or deliberate attempts to conceal or falsify a bettor’s position will be treated differently. GeoComply says that activity may be flagged for additional review and, depending on the circumstances and the sportsbook’s policies, could lead to account restrictions, suspension, or closure.
Sports bets are not all played under the same rulebook
Sports prediction markets like Kalshi and Polymarket look like traditional sportsbooks, but they operate under a different legal framework.
Sportsbooks accept bets under state gaming licenses, but prediction markets operate as exchanges where customers buy and sell event contracts with other traders, Chaffee said.
Prediction markets are regulated by the federal government, but a growing number of states are contesting whether they should also be regulated by state gambling laws. Different rules can affect who can use the platform, where they can trade, and what makes or loses money.
Most sportsbooks require customers to be 21 years of age or older, but Karshi allows customers to be 18 years of age or older. Prediction markets are also available in some states where traditional sports betting is illegal, Chaffee said. However, customers still need to verify their identity.
It’s also important to read individual contract terms carefully, Chaffee says. These terms determine exactly what will happen to pay out the contract, including what happens if the match is postponed or not held by the specified date. If you get these wrong, you may be right about what’s happening on the field, but you could end up losing money on the contract.
Disclosure: CNBC and Kalsi have a commercial relationship that includes customer acquisition and minority ownership.
