A progressive jackpot grows because players feed it. The seed, the contribution rate, the reset, and what operators must tell you.
A progressive jackpot is a prize that grows because players feed it. Every bet on a qualifying game sends a small slice to a shared pool, the pool climbs until somebody wins it, and then it resets to a starting figure and starts climbing again.
That is the whole mechanism. The parts worth understanding are where the slice comes from, what the starting figure is for, and what the operator is allowed to do with the pool once it exists.
South Dakota's gaming rules put the basic shape in plain language. Under Rule 20:18:17:24 a progressive slot machine is defined as one "with a payoff that increases as the slot machine is played", the starting jackpot "must begin at or above the top award", and the jackpot "must be permitted to remain until it is won by a player".
It comes out of your stake, not out of the operator's margin.
This is the part most coverage skips. A game with a progressive attached does not pay the same base prizes as the same game without one. The contribution is carved out of the prize budget first, and what is left funds the ordinary wins. That is why a jackpot game can feel colder between features than a flat game at the same stated return.
In Britain this is not optional. RTS 9 of the Gambling Commission's remote technical standards requires that "an explanation of the jackpot rules must be clearly available to the customer before they commit to gamble".
The implementation guidance attached to that requirement is specific about what the explanation should contain: how the jackpot is funded, its starting seed, any ceiling value, the return to player, how prizes are decided and awarded including what happens if two players trigger the same jackpot at almost the same moment, and, where the jackpot is capped, what happens to contributions above the cap.
If you cannot find those details on a British licensed site, the information is missing and you are entitled to ask for it.
Take the pool away. RTS 9 also requires that jackpot systems "must be configured and operated with adequate fairness and security", and its guidance says that where a jackpot holding player contributions is decommissioned, those contributions should be returned fairly, with priority to the players who paid in.
Nevada says the same thing harder. Regulation 5.110 states that the incremental amount of a progressive payoff schedule "is an obligation to the licensee's patrons", and a licensee that stops running the progressive for any reason, including a change of ownership, must arrange for that obligation to be satisfied in a manner the Chair approves. Under the same section a licensee may not reduce or eliminate a progressive at all unless a player wins it, a malfunction is being corrected, the money is moved to a similar progressive on the same premises within 30 days, or the regulator approves an exception in writing.
So a jackpot that quietly disappears is not a normal commercial decision. In a regulated market it is a reportable event with money owed behind it.
The types of jackpot are covered in progressive, pooled, local and fixed jackpots. The price of a jackpot is covered in what the odds on a jackpot really are. What the pool costs the base game is covered in does the jackpot lower the RTP of the base game. For the terms themselves, see the glossary entries for jackpot and RTP.
UK Gambling Commission, Remote gambling and software technical standards, RTS 9 Progressive jackpot systems. https://www.gamblingcommission.gov.uk/standards/remote-gambling-and-software-technical-standards/rts-9-progressive-jackpot-systems
Nevada Gaming Commission Regulation 5, section 5.110. https://www.gaming.nv.gov/siteassets/content/regs/gaming-statutes--regulations/regulation-5-as-of-04-26.pdf
South Dakota Administrative Rule 20:18:17:24.
| What to check | Where it should be | What it tells you |
|---|---|---|
| Seed value | Jackpot rules | How far the prize falls after a win |
| Contribution rate | Jackpot rules or game info | How much of your bet leaves the base game |
| Combined or split RTP | Game info screen | Whether the headline return includes the jackpot |
| Eligibility | Jackpot rules | Whether your stake size can win it at all |
No. On almost every progressive the trigger is random on each qualifying spin, so a pool that has run for six months is no closer to paying than one that reset this morning. The prize is bigger. The chance is the same. The exception is a jackpot with a stated deadline, covered on the must drop page.
Mathematically the value of the jackpot component does rise as the pool grows, because the prize goes up while the chance stays flat. Whether that makes the whole game a better bet depends on the base return, which is usually lower on jackpot games in the first place.
Usually the supplier operates the pool across every casino running the game, and the casinos feed it. That is what makes network jackpots so large. For an in house jackpot the casino holds it alone.
Regulatory statements are sourced to UKGC RTS 9, Nevada Regulation 5.110 and South Dakota Rule 20:18:17:24. Explanations of how jackpots are funded are general guidance. Last reviewed October 15, 2026.