Back vs Lay Bets in 2026: Lay Liability and How US Prediction Markets Do It

The quick answer

• Back bet: you bet that something happens. You risk your stake to win stake x (decimal odds - 1).

• Lay bet: you bet that something doesn't happen. You win the backer's stake and risk the liability.

• Lay liability: backer's stake x (decimal odds - 1). Laying $100 at 2.50 means risking $150 to win $100.

• US access: Betfair's terms don't allow accounts for anyone located in the United States.

• US equivalent: on a US prediction market you buy the other side, a No contract or the opposing team. Your liability is what you pay for it.

• Cost: on Novig a pre-game straight trade carries no fee for either side, so buying the other side before the game costs only the price. A Kalshi taker pays about $4.20 on the example below.

Laying a bet means taking the bookmaker's role for one bet: someone backs a team at your price, and you pay them if it wins. Your upside is capped at their stake and your downside is the liability, which grows with the odds.

US bettors can take the same position without Betfair. A No contract at 60c, or the other team at 60%, pays the same as laying at 2.50.

What backing and laying mean

Betfair's help center says "To lay a bet is to back something not to happen." Its example is laying Manchester United, which wins "if they either lost or drew their match."

A back bet is the ordinary bet. Back a team at decimal odds of 2.50 for $100 and you get $250 back if it wins, $150 of it profit. A sportsbook takes the other side of every back bet. On an exchange another customer does, and that customer is the layer.

"In a lay bet, you always stand to win the stake of the opposing bet," Betfair says. The layer puts up the backer's potential profit, and that amount is the liability.

How we checked

Every rule and fee below comes from the venue's own pages, opened on 6 October 2026 and rechecked on 7 October: Betfair's help center and general terms, Novig's help center and the Ludlow Exchange rulebook (version 1.3), Polymarket US documentation, and Kalshi's help center, fee-schedule page and fee-schedule PDF (effective 7 July 2026). The worked examples use illustrative prices and are computed to the cent.

How to calculate lay liability

Liability = backer's stake x (decimal odds - 1)

Lay a team at 2.50 for a $100 backer's stake:

• Liability: $100 x 1.50 = $150.

• If the team loses: you keep the backer's $100.

• If the team wins: you pay the backer $150 of profit, which is your liability.

The pot is $250, the backer's $100 plus your $150, and the winner takes it. In Betfair's own example, laying golfer Tommy Fleetwood at 32 against a £10 backer stake carries a liability of £310, and Betfair notes the payout of £320 "includes the stake from the backer."

At 1.50 the same $100 lay carries $50 of liability. At 13.5, the price Betfair uses for a soccer draw, you "have to risk £125" for every £10 you want to win.

Betfair takes the liability from your balance, "as this is your worst case scenario," and charges commission only on net winnings in a market, at a rate that depends on where you live and your rewards package.

Why US bettors can't lay on Betfair

Betfair's general terms list "the United States of America (and US territories)" among its Prohibited Territories, and the terms say Betfair does "not permit Accounts to be opened by persons who are located in" them. A US sportsbook takes the other side of every bet itself, so there's no lay option there either.

How a prediction market expresses a lay

US prediction markets don't list a lay option. Each contract has a Yes and a No side that pay $1 between them, so buying No on a team is the same position as laying it.

Polymarket US's documentation says "To trade against an outcome, you sell YES (which is the same as buying NO)." In Kalshi's API documentation, a Yes bid at $0.60 is equivalent to a No ask at $0.40. On Novig, the basketball winner contract pays the Yes side $1.00 if the named team wins and the No side $1.00 if the other team wins, per the Ludlow Exchange contract terms.

Decimal odds of 2.50 are a 40% implied probability, so laying the team at 2.50 corresponds to buying its No side at 60c.

The two columns are the same position. To size it, divide the profit you want by (1 - No price): $100 / 0.40 = 250 contracts, which cost 250 x $0.60 = $150.

On a prediction market the liability is the price you paid, and you can't lose more. Novig's help center says winning contracts pay $1 and losing contracts $0, and its exchange checks before accepting an order that your account covers "its maximum loss under the Contract(s)." The Ludlow rulebook adds that all member positions "are fully cash collateralized."

Laying the 13.5 draw for a $10 win converts to buying the draw's No side at about 92.6c: 135 contracts for $125, the same £125-for-£10 shape as Betfair's example.

What the other side costs

Fees on the 250-contract No position at 60c, taken from the order book:

Novig's fee page lists pre-game straight trades as "No fee" for both maker and taker, and its makers pay $0 on every trade type. Polymarket US pays makers a rebate, $0.75 on this position at its 0.0125 coefficient, which favors anyone posting rather than taking. Polymarket US changed some fees again on 7 October 2026, so check its current schedule before relying on these figures. Kalshi's fee-schedule page lists $0.07 to $1.75 per 100 contracts for taker fees on most markets and showed no upcoming fee changes on 7 October.

Where the comparison breaks

Three-way markets: laying a soccer team covers both the draw and the other team, as Betfair's Manchester United example shows. On a prediction market that doesn't work unless the venue lists a Yes/No contract on that one outcome. Buying the other team instead leaves the draw uncovered.

Odds format: Betfair quotes decimal odds and US prediction markets quote cents or percentages, so a 60c No converts to a lay at 1 / (1 - 0.60) = 2.50.

Getting out early: a Betfair layer can back the same selection later, which Betfair calls trading. On Novig, selling "places an offsetting order on the opposing side of your original trade" at the best available price, which can be more or less than you paid.

What to look for

• Liability: work out stake x (odds - 1) before you place a lay, or price x contracts before you buy a No.

• Settlement: check whether the market is two-way or three-way before treating "the other team" as a lay.

• Fee: check what the side you buy costs. On Novig a pre-game straight trade carries none, and the same No bought in-game carries a fee.

• Exit: check whether the venue lets you sell the position before settlement, and at what price.

Back vs lay FAQ

What is lay bet liability?

Liability is what a layer pays if the selection wins: the backer's stake x (decimal odds - 1). Laying a $100 stake at 2.50 carries $150 of liability.

Can you lay bets in the US?

US bettors can't lay on Betfair, whose terms bar customers located in the United States. On US prediction markets they get the same position by buying the No side or the opposing team.

Is laying a team the same as backing the other team?

It is in a two-way market with no draw. In a three-way soccer market, laying a team also wins on the draw, so backing the other team covers less.

How much can you lose on a No contract?

You can lose the price you paid and no more. Contracts pay $1 or $0, so 250 No contracts at 60c can lose at most $150.

What does it cost to buy the other side?

On 250 contracts at 60c, a taker pays nothing on a Novig pre-game straight trade, $1.80 on a Novig live trade, $4.17 on Polymarket US and $4.20 on Kalshi. Polymarket US pays makers a rebate instead.

Sources

All opened 6 October 2026 and rechecked 7 October 2026, except where noted.

Betfair, "Exchange: What does the term 'Lay' mean and what is a Lay bet?", support.betfair.com/app/answers/detail/a_id/417

Betfair, "Exchange: What is Commission and how is it calculated?", support.betfair.com/app/answers/detail/a_id/413

Betfair General Terms and Conditions, clauses 4.1.6 and 4.2, support.betfair.com

Novig fee schedule: support.novig.com/en/articles/16195057-fees-on-novig

Novig, "What is Novig?": support.novig.com/en/articles/10336081-what-is-novig

Novig, "How Selling a Position Works": support.novig.com/en/articles/15948726-how-selling-a-position-works

Ludlow Exchange, LLC Rulebook v1.3 (posted 2 September 2026), Rules 5.2(f) and 6.1(b), via support.novig.com/en/articles/16075446

Ludlow Exchange basketball Winner class certification, Payout Criterion, via ludlowexchange.com/filings

Polymarket US, Orders & Trading: docs.polymarket.us/concepts/orders

Polymarket US fee schedule: docs.polymarket.us/fees (effective 1 October 2026; further changes effective 7 October 2026)

Kalshi fee schedule web page: kalshi.com/fee-schedule; fee-schedule PDF: kalshi.com/docs/kalshi-fee-schedule.pdf (effective 7 July 2026), opened 7 October 2026

Kalshi API documentation, Orderbook Responses: docs.kalshi.com/getting_started/orderbook_responses