It doesn't mean Groupon are getting you to pay their VAT though, the customer pays the VAT, it's just who accounts for it. If Groupon did pay it then they'd pay you £41.67 minus their commission. But they send you £50 minus the commission and leave you to account for it.
But that doesnt add up. If they take off VAT as source then as you say £41.67 is left of the £50. So with a 50% commission rate the payment into retailers bank would be half £41.67 so £20.83. But the actual amount that end up with the retailer is only £16.67.
This is how my accountant is handling it. I can only think that groupon have decided (and the contract signed is not clear) that groupon are entitled to 50% of the whole voucher price ie £25 AFTER Vat has been deducted. so the £41.67 becomes £16.67 after the £25 deducted. In essence they are taking commission on the VAT as well.
The way it is worded in the contact is "Success fee: 50% exc. VAT". In the small print it reads...
4.2 For any Voucher that is Validly Redeemed by a Purchaser with Partner, Groupon shall pay to Partner the Groupon Voucher Price less the
Success Fee and also less any amount in respect of Value Added Tax (VAT) chargeable by Groupon in respect of the Success Fee
(Groupons VAT). For the avoidance of doubt, Groupon shall retain the Success Fee plus Groupons VAT. That payment shall be made
within 7 of Groupons working days of Groupon receiving from Partner suitable and valid evidence (the nature of which may be stipulated by
Groupon from time to time) evidencing that the Voucher has been Validly Redeemed - which evidence Partner must: (i) provide to Groupon
using Groupons online partner redemption portal; or (ii) be sent to Groupon by post, fax or email; and for which, in both preceding cases,
such evidence must be received by Groupon within 28 days of the Voucher having been Validly Redeemed by the Purchaser of that Voucher,
with the Partner. If that evidence is not received by Groupon within that time, then Partner shall lose its right to receive any monies from
Groupon in respect of that Voucher (and Groupon may retain any monies that would have been so payable).
4.3 Save in respect of Groupons VAT, the parties agree and acknowledge that the payment or collection of any amount in respect of VAT (or any
fine, penalty, interest or surcharge imposed thereon) arising in connection with supplies made pursuant to this Agreement (Partners VAT),
the issue of any VAT invoice in respect of Partners VAT and the payment of any amount in respect of Partners VAT to Her Majestys
Revenue and Customs (HMRC) shall be the responsibility of Partner, as opposed to Groupon. If UK VAT law or HMRC practice changes
such that Groupon becomes liable to make any payment to HMRC for VAT (other than Groupons VAT), Partner agrees that Groupon may
unilaterally vary the financial provisions of this Agreement to produce the result which would have been achieved for Groupon, had that
change not occurred.
4.4 Groupon may set off against any amounts payable to Partner against any payment of any amount owed by Partner to Groupon (or to HMRC,
if HMRC does, or is likely, in Groupons reasonable opinion, to claim any VAT from Groupon); and any payment made by Groupon shall be
without prejudice to any claims or rights which Groupon may have against Partner.