Capital Gains and Conversion to Clean Units

[paulatscafell]

Hi All,
I hope you can help clear up my muddled thinking concerning capital gains and conversion from dirty to clean units. See below for details of an s104 holding and subsequent purchases, conversions (dirty to clean) and sales of some accumulation units I hold / held.
02/11/2015 - s104 holding: 48,278,2818 dirty units, cost £54,539.26, average cost per unit £1.130.
23/11/2015 - 22.4916 dirty units purchased (fund rebate), cost £33.40, price per unit £1.485.
26/11/2015 - Conversion 48,278.2818 dirty units to 46,649.1312 clean units.
17/12/2015 - 9.7843 clean units sold (platform fee), cost £14.97, price per unit £1.530.
05/01/2016 - 4882,8125 clean units sold (ISA), cost £7,500.00, price per unit £1.536.
18/01/2016 - 23.9794 dirty units purchased (fund rebate), cost £34.89, price per unit £1.455.
20/01/2016 - 15.5725 clean units sold (platform fee), cost £23.53, price per unit £1.511.
08/02/2016 - 23.8885 dirty units purchased (fund rebate), cost £34.71, price per unit £1.453.
19/02/2016 - 14.1277 clean units sold (platform fee), cost £21.46, price per unit £1.519.
16/03/2016 - Conversion 70.3595 dirty units to 67.7787 clean units (the 3 fund rebate purchases).
Due to an error I made last year, in selling more units than I meant to, I need to report and pay capital gains tax. My previous rough calculations now need to be refined. Are the dirty and clean units all one s104 holding or should I separate them until the second conversion takes place? I see two potential outcomes:
1) The sales of clean units on 05/01/2016 and 20/01/2016 should only be matched with clean units in the s104 holding.
2) The sales of clean units on 05/01/2016 and 20/01/2016 should be matched partly with subsequent purchases of dirty units using the 30 day ‘bed and breakfasting rule’ with the remaining units matched to the units in the s104 holding (a mixture of dirty and clean units).
Many thanks
Paul

[telemark15]

Did not look at all your transactions closely.

My understanding(I am not a tax professional):
-conversion (selling) dirty units to (repurchase) clean units of the same fund does not count as disposal and therefore no CGT implication.
-original cost of dirty units plus trading costs pro rota is the cost basis of the clean units
-any charge rebates of dirty units are refund of cost and should not be subject to income or capital gains tax

[GPhelan]

Agreed. Hargreaves Lansdown and Interactive Investor converted my funds in recent years and both emphasised that there was no CGT implication for converting to Clean units.
You can read the HL comments here: https://www.hl.co.uk/funds/fund-faqs in section 'FUND CLASSES / What is a Fund conversion?' which includes the summary "There are no charges to convert and HMRC has confirmed that conversions will not count as disposals for capital gains tax purposes. You will remain invested throughout the conversion process."