Early 1st postage dues on returned & stampless 30-5-1948 HAIFA - TEL AVIV mail

1948 early 1st postage rate period domestic taxed mail: 4-6-1948 commercial cover from HAIFA to TEL AVIV mailed unfranked tied by Haifa Head Post Office postmark configured unusually with Latin date above Hebrew date; front marked by Haifa "T" tax cachet and charged twice the deficiency, but as addressee initially not found (cachet on back) returned to sender where tax paid over 3 weeks later using 1st postage dues series 20m Ba #PD4 frank tied by 28-6-1948 TEL AVIV Head Post Office postmark; opened gently at back. A rare instance of tax paid on return of letter for being unfranked (not for a 'Return Fee'); the 1st series of Postage Dues entered use in Tel Aviv on 30 May, so this is an early Postage Dues cover; very fine.