Your interest will be paid gross from 6 April 2016
In the 2015 budget, the government announced that from 6 April 2016 a new tax-free Personal Savings Allowance would be introduced for individuals.
Interest paid on or after 6 April 2016 will be calculated using the gross rate. This means all the interest we pay you will be without tax deducted. For sole traders and individual partnerships, if the total amount of interest you receive exceeds any Personal Savings Allowance to which you’re entitled, you may have to pay tax at the applicable rate. This would need to be paid directly to HM Revenue & Customs. For more information, please visit gov.uk and search for 'Personal Savings Allowance'.
If you receive monthly or annual interest, any interest payments you receive before 6 April 2016 will be paid net, unless you've registered for gross interest or provided sufficient evidence to justify your gross tax status.
From 6 April 2016, all interest payments received will be paid gross, even if this is for interest accrued before this date.
Each individual will have a Personal Savings Allowance. With Santander if you have a joint account, the interest is considered split equally between the parties to the account. Your proportion of the interest will count towards your Personal Savings Allowance.