Backdated payments
If the Tax Credit Office receives your claim on or after 6 April 2013, they will only be able to backdate it up to one month. The same goes for reporting changes to your income. If you report a change that means your income goes up, the higher amount will only be backdated by up to one month. To make sure you get your higher payments backdated to the earliest possible date, you should report all changes within one month.