In order to apply for a tax refund from the UK, you need a statement of earnings. There are three types of statements:
P45 is issued when the employment finishes. If the employee starts work for a new employer during the same fiscal year, (s)he should give the new employer the P45 statement received from the previous employer, keeping only the first page (Part 1A).
P60 is issued to each employee at the end of the fiscal year. P60 form should contain data on the full-year (from 6 April 6 to 5 April) earnings of the employee, received both from the current employer and from previous employers for whom (s)he worked in the same fiscal year. P60 statement is given to employees who are employed on 5 April. If someone quits before that date, (s)he receives only P45.
Payslip – i.e. the settlement of weekly pay. If you have got neither P45 nor P60, the settlement can be based on payslips. However, due to the fact that for the tax authority these are not the basis for the settlement, you will need to contact the employer to obtain your Statement of Earnings or P11 (replacement documents). Payslips contain a breakdown of weekly earnings. In the UK, it is common to refer to numbered calendar weeks. According to this principle, the first week of the year is marked with number 1, and the last one – with 52. Week number is usually provided on the Payslip. Payslip contains information about the income of the week and total earnings since the beginning of the settlement period, which is the beginning of employment or the beginning of the fiscal year if the employment started earlier. Therefore, the payslip for the last week of work is the most interesting one because it contains overall information about earnings.