One thing about Betfair starting price (BSP or Betfair SP) which is not widely known is the minimum Betfair liability for lay bets. For example, when placing a normal lay bet at available odds, you are not limited to a liability. The only restriction is the minimum bet size which must be at least 2 pounds for UK customers. You can place 2 pounds even at 1.01 producing liability of only 2 * 0.01 = 2p. However if you are laying at Betfair SP the rules are completely different and it’s important to know them. It turns out that Betfair has a minimum LIABILITY for lay bets placed at SP. For UK customers it’s 10 pounds. For customers with other currencies it’s now well known, I was able find a clear size only for Australian dollars, which is $30. For all other currencies there is no information, Betfair only states that it’s “equivalent of 10 pounds in your local currency”. So if you want to know the limit in euros you probably have to use exchange rates to convert pounds to euros. If you try to place a lay bet at SP which gives a liability less than the minimum amount, the Betfair will not accept it with error “Bet is below the minimum permitted bet size.” (MINIMUM_PERMITTED_BET_SIZE). There is also a minimum liability for BACK bets at SP, but it’s the same as minimum permitted bet size of bets at regular odds i.e. 2 pounds for GBP. I wish there was more information on this topic because it’s hard to figure out why some bets are not being accepted.