Using exchange rates from HMRC

There are HMRC yearly average and spot rates and monthly rates from HMRC, available via https://www.gov.uk/government/publications/exchange-rates-for-customs-and-vat-yearly Could you advise me, please, is it correct that I can choose myself what rate type exactly to use from those options (potentially, among other types): those spot rates, those monthly rates, and those yearly average rates? If so, and if I use spot rates from HMRC, could you advise me, please, how can I choose an appropriate spot rate (from HMRC) to use for my taxes in the UK (income tax and capital gains tax)? Can any spot rate (from HMRC) be used for any date in the same calendar year as for the spot rate, or for any date in the same tax year as for the spot rate? Or, can the spot rate (from HMRC) that is the closest (in terms of the number of days) to a particular date be used for that particular date? For example, what spot rate(s) (from HMRC) can I use for dates in the tax year 2022-2023? For example, can I use the '[s]pot rates on 31 March 2022' for the dates in the tax year 2022-2023 that are closer (in terms of the number of days) to the 31st of March 2022 than to the 31st of December 2022 (or have the same distance in terms of days to both the 31st of March 2022 and the 31st of December 2022)? Thank you.

Hi
You can use any of the spot rates referred to in the guidance you mention as long as it is in the same tax year as the year you are doing the conversion.
So for something that happened in 22/23 would occur after 6/4/22 so you cannot use rates from March 22 or earlier.