A computer-based method and a system for adding and printing variable security data. The system includes a memory, a processor, and a printer. The memory stores received print data. The processor modifies the print data for adding variable security print data and sends the modified print data for printing. The printer receives and prints the modified print data. The variable security data may vary between different printing operations. The processor captures a portion of the stored print data based on data-capturing criteria and modifies the stored print data based on the captured portion of the stored print data. The data-capturing criteria may be user-defined and may include leading tag data, trailing tag data, matching tag data, or combinations thereof for indicating a relative position of the captured data.