What exchange rate should I use for dividend income?

My broker is depositing my dividend income from US companies in GBP, using an exchange rate that contains a service fee. So, on my dividend certificate the amount that I receive is in GBP with US tax already deducted. For the purpose of self assessment, should I report that income using the monthly rates that HMRC publishes and convert the USD net amount to pounds or use the GBP amount that I've received from the broker? The reason I think the manual conversion from USD to GBP is needed is because, SA form requires to provide the amount of foreign tax deducted as well and this has to be converted to GBP as well. The problem I have is that, obviously the amounts received will be slightly discrepant since the exchange rates are different.

Hi twdev,

You will need to convert the dividends yourself, using either the official rate on the day, which is reported in most national newspapers.  
Or, alternatively, use the official exchange rate at Exchange rates from HMRC in CSV and XML format.  
You are free to use the monthly, annual or spot rate.  
There is no tax relief for costs incurred in converting the currencies, as legislation adivses that there is no gain or no loss when converting,
which is why you cannot use the brokers figures.

Thank you.