Dorothy's income tax and Class 4 NICs liability for 2019-20 was £24,600, of which £600 was deducted at source. Her liability for 2020-21 is £28,000, of which none is deducted at source. She made a first POA in respect of 2020-21 on 27 February 2021 and a second POA on 12 September 2021. She also made a balancing payment for the year on 21 February 2022. All of her payments were for the correct amount.

(a) Calculate the amount of any late payment penalties payable by Dorothy in relation to 2020-21.

(b) Assuming an interest rate of 2.6% per annum, calculate the amount of any interest payable by Dorothy in relation to 2020-21.