I think 5.03/80 * 100 is the formula that you want to work in that direction then.
Bear in mind, you may have other allowances that mean you don't get taxed on all your interest earnings, make sure you've checked what you're entitled to and how much difference that might make.
Yes, thanks that's the formula. The interest on my taxable accounts this year is £8282.00. I realise I will have to pay HMRC 20% tax on £7282.00. I have more of less the same amount in ISAs as Taxable accounts. All taxable accounts are in joint names so my wife is in the same boat. HMRC keep a list, which can only be obtained by phoning them, of the untaxed interest paid to them by banks and building societies. I keep a list of the untaxed interest paid from the 6 taxable accounts. The HMRC list shows actuals and estimated figures and should only use the actual figures to calculate tax owed. In my case after phoning them of the 18 entries only 7 were actual the other 11 estimates. I eventually sorted mine out. In the case of my wife they actually used an estimated account to calculate her figure. If one takes out a 1 year fixed rate bond (taxable) and interest is paid on maturity, most banks will issue a new account number, so if a bank paid 1k interest that will be shown on the list as an actual for this year but for next year it will be shown as an estimate even though the account was closed on maturity. Next year I'm sure HMRC will push me on to Self Assessment which might be a blessing or a curse.
I suggest everyone keeps a record of their untaxed interest and if necessary contact HMRC and as for a print out of the information given to them by banks and building societies.
Thanks again for the formula
