I met my current boyfriend while renting a room in his brother's house (he was also renting a room there). We dated and after a few months I moved out with my daughter to my own flat. My boyfriend stayed living at his brothers but wasn't working and couldn't claim housing benefit so him and his brother were at loggerheads. I held a single person Tax credit claim for the last tax year as we werent in a serious relationship to start and didn't actually live together. I discovered I was pregnant a few weeks after moving and we decided to keep the baby but carry on our living arrangements as we were i.e he didn't move in as we wouldn't be able to afford living that way. But my boyfriend's brother started opening his post as he was annoyed he couldn't pay rent and was asking for his jsa so he asked the jobcentre to hold his post there for him. When he finally got a job in February, he used my flat as an address so his payslips would be secure. In May he and his brother had patched up their differences as my boyfriend was making rent payments from his wages and his brother moved in with his girlfriend. His brother said we could rent his whole house if we wanted to live together. This was great as it meant we would be able to afford the rent and meant that we could finally be together properly for when the baby arrives in July. I did my tax credits renewal and declared my change of address as I moved back into his brothers house, letting them know that I was moving in with my boyfriend. They said that I needed to end my single claim because we would need to make a joint claim. So I did that and have a small overpayment amount from the 23rd May when we moved in and them ending my last claim. When I called them to ask about how I date the joint claim (as it doesn't start til the 23rd May and the form says it gets backdated to the beginning of the tax year or for one month, whichever is shorter) They said that I should have had a letter about an undeclared partner on my last claim. When I asked, they said it was sent at the end of May to my old address, but obviously I haven't got it. So they took my details and said a case worker would call me back. I don't know what they mean about undeclared partner, he wasn't living with me, although he stayed a few times, but I am really worried that they think he was living there because of his payslips and p60. I don't know if I have done something wrong now, I feel like I may have committed benefit fraud unknowingly, and its making me feel awful. I just don't know what to do :( I know I shouldn't stress what with the being pregnant and baby due in just 4 short weeks, but I am TERRIFIED to the point of I keep vomiting with worry. Please can someone help?