How Koinly counts exchange rates?

[Tom]

Hello everyone.

How Koinly counts our profit based on different currencies? Where can i find exchange rates and what’s the procedure? I would like to know that before HMRC will ask me

Let’s say i bought ADA for USDT so i made following transactions:
8 of Jan bought 150USDT paid 100GBP with GBP/USDT rate 1.5 and after bought 300 ADA for 150USDT.
9 of Feb sold 300 ADA for 151 USDT so my profit is 1USDT but on that day GBP/USDT rate is 2.0.

For tax purposes my 1USDT profit in GBP equals 0.5GBP using GBP/USDT rate 2.0 or 0,67GBP with 1.5 GBP/USDT?

[europa]

I think (not tax advice) the way HMRC view it is that every part of your transaction chain needs to be referenced back to GBP. So it would be something like this:

Buy 150 USDT / cost basis 100 GBP
Sell 150 USDT / taxable gain 0 GBP
Buy 300 ADA / cost basis 100 GBP
Sell 300 ADA / taxable gain = whatever the ADA price is in GBP minus 100 GBP
Buy 151 USDT / cost basis = 75.50 GBP

Koinly uses market price feeds for its cryptos so I assume it also uses forex feeds timestamped to each transaction, to produce the GBP values.

I don’t fully understand Koinly’s cost calculations but my approach is to assume that it will be sufficient to show HMRC that I have used a recognised service to produce the figures. HMRC guidance says that you have to use reasonable measures to establish market prices - using Koinly seems as reasonable as any to me.