Tax Returns

If we never signed up for Child Benefit, I don't have to do anything right?

Correct. The two reasons to sign up for it even if you have to pay it back via HICBC are:

• To protect NI contributions for one of the parents if they're not working for a period (the CB has to be setup to be payable to them for this to work)
  
• If you're doing SA anyway and want to stick the money away somewhere and invest it before it has to be paid back to HMRC
  
  

We decided to keep receiving CB for both reasons. Mrs GB decided to have some reasonably long stints without work and so her NI payment history is protected (if we ever see any form of a state pension is another matter).

Also I generally do SA each year to claim back tax from gift aid donations, so receiving CB and notionally sticking the money away somewhere means I've made a bit of money from it before having to give it back to HMRC.