yes that happened to my husband ....he didn't make installments thru the year and he got an interest bill...yes 5 LM I just send monthly payments to the government ( I chose the amount so I hope I don't get an interest bill) and for me I would rather send it to the government every month then trust myself to save it ...it just works better for me ....and I made it part of my budget so its affordable. I use internet banking so the heading was revenue Canada instalments