There seems to be general consensus that these rules apply for crypto tax accounting in the UK:
When you dispose of shares you can’t work out your capital gain or loss until you’ve matched the shares disposed of with shares you acquired. You’re treated as disposing of shares in the following order:
First: Shares acquired on the same day as the disposal (the ‘same day’ rule).
Second: Shares acquired in the 30 days following the day of disposal (the ‘bed and breakfasting’ rule) provided the person making the disposal was resident in the United Kingdom at the time of the acquisition.
Third: Shares in the Section 104 holding (pool of all purchases not under First and Second).
https://www.gov.uk/government/publications/shares-and-capital-gains-tax-hs284-self-assessment-helpsheet/shares-and-capital-gains-tax-hs284-self-assessment-helpsheet
Comments:
We N. on 12/28/2017
The Queen insists on bed and breakfasting.https://www.gov.uk/government/publications/shares-and-capital-gains-tax-hs284-self-assessment-helpsheet/shares-and-capital-gains-tax-hs284-self-assessment-helpsheet
Stuart J. on 04/11/2018
If it sounds nuts, there is a reason for it. UK CGT has a high personal allowance, where you are not taxed gains up to a threshold (~£11K). So what people would do, is sell their shares near the end of the tax year, and buy them back the same or next day. This would reduce the tax liability, and thus reset the cost bases.That's why UK users of this service need this.
Stuart J. on 04/16/2018
I believe this would also be a useful option for those countries that forbid Wash Selling.