Many, MANY years ago (I think it was in 2001) I created a self-calculating pdf form which landlords could use to create a schedule of rent arrears.
It was a bit unsatisfactory in many ways but it did the job. From time to time I thought about updating it but by then I had forgotten how I had done the self-calculating fields.
I also wondered about doing a spreadsheet version, but I am not very good with spreadsheets so had left it for a rainy day.
However, when developing this new website I decided that my elderly form really MUST be replaced. The logo at the bottom was wrong for a start. So I took the easy route and got someone from the freelancer website Upwork to do it for me.
While I was at it, I got them to do an excel spreadsheet version too – so these are now both on the site, linked both from the main Documents page and from the Rent Arrears Action Plan (stage 2).
I strongly recommend that you use them – or something similar – when recording your tenants rent arrears. Being self-calculating they also ensure that there are no maths errors!
You will find them here (logged in Landlord Law members only).