PCInk - 12:33 pm on Nov 19, 2008 (gmt 0)

The standard most companies I deal with (in the UK) are 30 days from end of month.

This means if you invoice in January (and it doesn't matter if it is the 1st or last day in January), payment should be made by the end of February.

This way, all of January's invoices (if there are a number of them) should be paid together.