I see that BetFred is listed as No Negative Carryover here.
However I've looked at their Terms and it says :
Seems pretty clear that negative carryover can be applied, even if they're not currently enforcing it.In the event that a Revenue Share in any calendar month is a negative amount, Betfred shall be entitled but not obliged to carry forward and set off such negative amount against future Revenue Shares which would otherwise be payable to you. However Betfred shall also be entitled but not obliged to zero the negative balance that would otherwise be carried forward.
I'm not sure how long that has been in the Terms, however I did find a thread mentioning it on the GPWA forum in January 2012, and in fact a representative from BetFred wrote :
It seems they want to keep it in the terms, even if they're not enforcing it.Agree that 6.5 is a bit vague, it is a term that is repeated in the T&C's of many affiliate programmes that don't in fact enforce any negative carryover so in that respect Betfred are no different from anyone else but I agree that it might be possible to improve the wording. I'll see what I can do with that one.