any incumbrance, is more than two hundred pesos but not more than two thousand pesos, fifty centavos. When it appears that the amount of the documentary tax payable hereunder has been reduced by an incorrect statement of the consideration in any conveyance, deed, instrument, or writing subject to such tax, the Collector of Internal Revenue, provincial tre asurer, or other revenue officer shall, from the assessment rolls or other reliable source of information, assess the property at its true market value and collect the proper tax thereon. aHTcDA 2. For each additional one thousand pesos, or fractional part thereof, of such true consideration or value, fifty centavos. (y) On every charter party, contract, or agreement for the charter of any ship, vessel, or steamer, or any letter or memorandum or other writing between the captain, master, or owner, or other person acting as agent of any ship, vessel, or steamer and any  other person or persons for or relating to the charter of any such ship, vessel, or steamer, and on any renewal or transfer of such charter, contract, agreement, letter or memorandum: 1. If the registered gross tonnage of the ship, vessel, or steamer is not more than three hundred tons, six pesos. 2. If the registered gross tonnage is more than three hundred tons but not more than six hundred tons, ten pesos. 3. If the registered gross tonnage is more than six hundred tons, twenty pesos. ( z ) Upon each and every assignment or transfer of any mortgage, lease, or policy of insurance, or the renewal or continuance of any agreement, contract or charter by altering or otherwise, a stamp tax shall be levied, collected, and paid at the same rate a s that imposed on the original instrument. [2339-30.] S ECTION  1605 . Documents and Papers not Subject to Stamp Tax . — The following instruments, documents and papers shall be exempt from the documentary stamp tax: ( a ) Bonds, debentures and certificates of indebtedness issued by the 477 Copyright 2012 CD Technologies Asia, Inc. and Accesslaw, Inc. Philippine Law Encyclopedia 2011