I did mine mid November. The issue I had is that I didn't have the figures back for previous years and the self assessment payment is due end of Jan. You can setup a payment plan, but only one, so I needed to know my previous year figures to combine with the 18-19 self assessment figure. I called them and they finally completed the previous years calculations this week.
Just to back this up.
I am in a payment plan to pay back a large figure, which covered 2013/2018. I requested this, as I would pay the 2018/2019 when it was due after self assessment. HOWEVER, this means that any payments you make (for the previous tax year) have to be done over the phone manually and assigned to the balancing payment specifically. OTHERWISE, the system will automatically allocate it to the oldest balance, which they WILL NOT tell you till you get warned for being overdue for the previous year (BY POST). EVEN IF you specifically select the year in question on the website and pay the exact amount of the balance. This also will screw up your direct debit for any previous payments, as the payment is ALWAYS allocated to the oldest amount again.
Fixing this is difficult, and has to be explained to the representative to ensure that they move it to the correct allocation. I was told that this was impossible by one, and then magically after I complained it was sorted. Most of the representatives are NOT aware of this process/issue. So this takes a lot more hold time whilst they "work it out".
I have been told by 3 different people at 3 different times, that I was up to date, and two times I received letters or notification that I STILL owed another amount. The latest was today (just now), after paying another £500ish "Penalty" that was, for some reason, not rolled up in my previous payment plan which covered the years i was being penalised for...
Shambles... total shambles, and it requires a LOT of work to attempt to understand their processes, and its no wonder people fall through the cracks, and end up falling foul of the system.
