It is very easy to pass on STDs and STIs including HIV by anal sex as the lining of the rectum is very thin (it is thinner than the vagina) and so small tears and transmissions are quite common. Better2Know would suggest a full STD Screen.
Specifically for those receiving anal sex, Better2Know would recommend a chlamydia and gonorrhoea test of your rectum. This test would take a small swab from your rectum, and your results would be ready in two days.
Everyone’s circumstances are different, and it is your responsibility to choose the tests that are right for you depending on your sexual activity and what you know about your partner. If you are unsure then Better2Know recommends a Full STD screen. Once is enough to catch an STD, STI or HIV.