SA Pentalty received

At the weekend my wife received a penalty letter for not sending her Tax Return in time. She had in fact completed it online on 3rd January

and was convinced that it had been submitted as she got a submission receipt numbber detailed on the form she had downloaded

to her computer. When she printed the 10 page form, it was only then that she noticed on page 1 that it stated that it had not been submitted. She immediately wrote to them to appeal. I would assume that a receipt number issued would only be issued once actually received. We await HMRC response.