Betfair today just massively increased the size of their Premium Charge "net", which is now going to catch an awful lot more people and cost those people an awful lot more money. The size of the charge has gone from 20% to 40%-60% and the threshold needed to be hit with the charge has also doubled. New rules apply from July 18th. This doesn't even take into the account commission that you're already paying them, so some people could be paying Betfair 65% of their winnings.
Put simply, previously you had to generate less commission than 20% of the amount you won to pay the charge. Now, you have to generate less than 40% of the amount you won in commission to be liable, and if you are liable, the charge will be at least double what it was before. There is a minimum lifetime net profit of £250,000 but unfortunately that doesn't save me either.
Example:
Let's say you've won £400,000 overall. Previously, as long as you'd generated at least £80,000 (20% of your winnings) in commission, you'd be exempt from the charge. If you were a bit under £80,000, you'd be liable for the charge but there was a £1,000 allowance before you had to pay it, and the amount you'd be liable for would be fairly small.
Now under the same circumstances, if you'd won £400,000 and generated £80,000, you'd be paying Betfair at least 40% of your winnings, and likely 50% or 60% depending on the exact figures, each week. Of course when you have a losing week, there is no rebate so you lose both ways.
My commission generated is about 35% of the amount I've won, so it's got me and there's little I can do to escape. If I open another account under another name, I'll likely to be paying the Premium Charge virtually from the start. If they catch me doing that I'll likely be banned from the site anyway. The only way to avoid the new charge will be to initially lose a large sum and then once my commission generated gets to 40%, win less than I do now.

Overnight, I suddenly cannot use Betfair at all as of July 18th. This is particularly true as I use Betfair for hedging other positions and occasionally arbing (which was originally to avoid the PC).
I do tend to use Betfair for hedging long-term football bets on occasion. For example let's say next football season I backed Chelsea to win the league. Victor Chandler and a few others are joint best price @ 11/4. If I stuck £40,000 on Chelsea (to potentially win £110,000), I might decide that I want to hedge my bets slightly if they open up a 10-point lead at Christmas. I could go to bookmakers and back all of the other contenders at best price, but it's much easier and you'll nearly always get a better price by simply laying Chelsea on the exhanges. So in this example, let's say Chelsea are 1.3 at Christmas with their 10-point lead. Roughly speaking, at this point I'd want to be laying £116,000 @ 1.3 to ensure a profit of about £76,000 either way. Let's assume that Chelsea then fail to win the league. I've won £116,000 at Betfair (a little bit less after commission), but then Betfair help themselves to 60% of this amount (£69,600), so in fact when everything is taken into account, I've actually only won £4,000 or so. If Chelsea had won the league, I'd have lost £34,800 at Betfair, thus greatly helping my future Premium Charge position and making it unlikely I'd pay it that week in May, and won my bet at Victor Chandler and thus would be £76,000 up. If I'd actually backed Chelsea at Betfair originally, I'd be screwed either way whether they won the league or not, unless I could find a way to lose about £76,000 on other bets the week that the league title is decided. The position is now that I simply can't afford to win at all at Betfair while I'm below their 40% threshold, and any big wins are suicidal as they'll just help themselves to most of the winnings.
You'll have to excuse all the waffle here, but I'm not the only person today who is absolutely raging. This is a life changing decision for me that Betfair have made today, and has me seriously looking at a career change three weeks from now.

I am going to initially attempt to use Betdaq to do pretty much what I do now, but Betdaq are massively inferior to Betfair in so many ways and offer nowhere near the same amount of markets and very little in-play. The amounts of money being traded on most things is massively lower than Betfair, although liquidity in certain markets has massively improved over the past year or so. No bookmakers will take any bets from me, no matter which of my many identities I use, so betting with traditional bookmakers simply isn't an option. Betfair have taken this decision to screw some of their more successful customers because their share price has fallen by 50% since they floated. The chief executive announced he was quitting yesterday, although he is likely being forced out by investors very unhappy with the way the shares have performed. Put simply, Betfair need to generate more revenue and they have decided that this is the best way to do it. I was only saying to some a couple of weeks ago that I was expecting Betfair to increase their charges this summer due to the way the shares were performing. I thought they'd do the Premium Charge first as increasing the base commission rate would probably generate more of a stir. I didn't anticipate the massive hikes that they announced today, it is astonishing that they have decided to do this. I assume they'd maybe increase the charge from 20% to 25% or increase the commission generate threshold in the same way. Instead it's more than doubled.
It won't stop there either. The base commission I would imagine won't remain at 5% indefinitely. They'll be looking for ways to squeeze more money out of people that way too. Betfair used to advertise using the slogan "Winners Welcome". Now, they are just as bad as any bookmaker who won't take any bets. The only people Betfair wants are losers and possibly those who break even. If you win and have the cheek to actually win and take money from the exchange, Betfair will be taking a large slice of that money first.

I wouldn't be surprised if Betfair start seeding their own markets to make up for all the market makers and layers who will now go elsewhere.
Final point is that many people reading what I've just written are probably thinking serves you right, I don't care, it won't affect me, or things to that effect (and worse!).

I'm well aware that probably no one else here is likely to be affected by the Premium Charge. However from July 18th, if you actually bet on slightly more obscure markets at Betfair, such as perhaps correct score in football outside the Premier League, American Sports, golf (apart from outright winner markets), Scottish football and so on, then don't be surprised if when you go to place a bet, all you are confronted with is a near blank screen with virtually no money in the markets at all, or at least nothing at any sensible price. It's difficult to predict exactly what will happen, but if Betdaq or anyone else get their act together and offer a credible alternative, then Betfair have just signed their own death warrant with what they've done today.
All would be rosy if I could just become friendly with Paul Merson and persuade him to let me use his Betfair account.....