... boxes Use this form between April 2012 and April 2013, to claim tax credits For information on backdating your claim, see Notes, inside cover Use the Notes, Getting your tax credits claim form right, ... Your tax reference You will find this on your tax return 4.11 Your tax reference You will find this on your tax return 4.12 If you have not yet sent us your first tax return, enter the date you ... Backdating your claim We can normally only backdate your tax credits for up to one month from the date we get your claim So, to avoid losing money make sure you claim straightaway You will need to ask...