A stamp which certifies that a weekly payment has been made towards National Insurance.
〈英〉保险印花（证明已向国民保险交纳过周保险费）
he had to pay sixpence a week for his insurance stamp
Example sentencesExamples
However, a significant number of those who emigrated in the 50s and 60s obtained enough insurance stamps to qualify.
Out of this his employer stopped 4d for his insurance stamp.
To have that sort of pain and to have paid national insurance stamps and then not be able to get a dentist and have to suffer like that is pretty disgusting really.
The basic pension is £75.50 a week but, like most women, I don't get the full amount because I didn't get enough national insurance stamps.