1951 domestic taxed mail: 9-7-1951 commercial cover from company in HADERA to insurance department of business in TEL AVIV, franked 10pr instead of the DO-2 postage rate period rate of 15pr, but sender incorrectly used a 10pr 1948 revenue label (Ba-REV.3) which was not accepted at the Post Office - but cancelled against regulations, whereupon the postal clerk re-applied the postmark on a blank corner of the field on cover's front, circled the incorrect franking and applied a 30pr tax (twice the full rate - here no concessional discount of only the missing postage, as addressed to a business); backstamped same day TEL AVIV-20 arrival; slit open at top, small piece missing top right.