billing previous employer for piecemeal work

[bortman]

On June 1st I left my 20-year position at a university research lab.

Since I've left I've been asked for assistance with a few minor issues. I expect to get more questions -- mostly minor stuff, but possibly some that are more involved -- in the coming months. I'd like to set up some way of tracking and billing for time.

I keep a simple spreadsheet to track time, but I don't know what wording to put into a contract or invoice.

I'd also like to know if there is a generally-accepted way to set hourly rate? My first thought was to charge 2.5x my hourly rate while I was employed.

I plan to charge a minimum of 15 minutes for any work that I do.

Anyone out there with thoughts on this, or experience with billing a previous employer?

[Linea_Norway]

Why not use the word "consultancy". They are consulting you for information.

I think you should first make a deal with your former boss and agree on you billing them. If you wait a few months until you have answered many questions, the bill might be large and they might not want to pay it if the bill comes as a surprise for you. If you get a deal, they can ask you questions with good conscience and you can answer without feeling taken advantage of.

Counting a minimum for every started 15 or 30 minutes is a good idea.