Hmrc p2p rules

You can offset losses against P2P income from other platforms if you don't have sufficient Lendy income.

My specific query relates to  offsetting P2P capital losses crystallised in 2017/18 against p2p interest paid in earlier tax years.

I appreciate I can offset p2p capital losses against p2p interest earned in the same year and that I can carry forward any unused p2p capital losses to offset against future p2p interest (and even across other p2p platforms).

The HMRC rules don't specifically allow me to offset p2p capital losses retrospectively against p2p interest earned in previous tax years. Confirmation on this would be appreciated (or hopefully an explanation as to why I am wrong and that this could be done. e.g. Could I reasonably argue to HMRC that although not expressly permitted in their rules it is within the spirit of the p2p movement that one shouldn't have to pay tax on an investment that ultimately made a net loss after taking into account the actual capital repayment and interest earned. 

My predicament is that I am getting out of p2p and so I will have p2p capital losses in future years but no p2p interest to offset it against.

i.e. I anticipate a 25% haircut on Leatherhead, a 50% haircut on the multi Gloucester loans and a likely 33% or more haircut on the Exeter loans (Thanks again Lendy - your due diligence and instructions to valuers are shite).

Word of warning. Get out while you can!