1633
The breach may be the most extensive since 2015 , when thieves gained access to the tax returns of over 300,000 people by using stolen data and filed fraudulent returns to get refunds .
 ( data breach: gained access,  thieves: attacker, get refunds: purpose, people: victim, 300,000: number of victim, using stolen data and filed fraudulent returns: attack pattern) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: phishing, data breach, ransom, discover vulnerability, patch vulnerability, Arguments type: vulnerable system, capabilities, vulnerability, number of victim, issues addressed, compromised data, damage amount, common vulnerabilities and exposures, victim, patch number, number of data, tool, discoverer, time, purpose, place, payment method, releaser, vulnerable system version, attacker, supported platform, patch, price, vulnerable system owner, trusted entity, attack pattern. 
Text: {0} 
Answer:
 ( data breach: gained access,  thieves: attacker, get refunds: purpose, people: victim, 300,000: number of victim, using stolen data and filed fraudulent returns: attack pattern) 