It's up to the state attorney general to decide whether to file criminal charges. Sanford's lawyers have claimed the allegations involve minor and technical aspects of the law.
The second-term Republican governor has been under scrutiny since he vanished for five days over the summer, reappearing to tearfully admit to an extramarital affair with a woman in Argentina he later called his "soul mate."
A series of Associated Press investigations into his travel showed the governor had for years used state airplanes for political and personal trips, flown in pricey commercial airline seats despite a low-cost travel requirement and failed to disclose trips on planes owned by friends and donors.
The State of Columbia newspaper also questioned whether Sanford properly reimbursed himself from his campaign cash.
The ethics commission conducted a three-month probe into the allegations, details of which have been awaited anxiously by legislators contemplating whether to force Sanford from office in January a year before his term-limited tenure expires.
The panel announced last week that Sanford would face "several" charges but did not reveal the specifics until Monday.
The governor's lawyers last week characterized the accusations as minor and technical and predicted Sanford would face no criminal repercussions.
The attorneys also said they looked forward to mounting a defense against the charges when the ethics panel holds a hearing into them early next year. They also confirmed that Sanford - as the state investigation was being conducted - added disclosures of his private plane flights to his ethics forms.
For months, Sanford has insisted he did nothing wrong and served as a better steward of the taxpayer dollar than his predecessors. But the former congressman's penchant for riling fellow Republicans who control the Legislature has left him with few allies since the startling June news conference during which he admitted to the affair.
Four GOP lawmakers already have filed a resolution that would force Sanford from office because of "dereliction of duty," and the travel allegations play no part in that move. Their measure deals solely with Sanford's absence from the state, when he led his staff to believe he was hiking the Appalachian Trail while he was in Argentina.
A committee that will consider that measure is scheduled to meet for the first time Tuesday.
Sanford has brushed off repeated calls from his own party to step down and in the past month scored a political victory by helping land a Boeing Co. assembly plant that is expected to bring thousands of jobs to North Charleston.
Meanwhile, the first lady and their four sons moved out of the governor's mansion. While the Sanfords have said they were trying to reconcile, Jenny Sanford more recently has described the two as separated. She is writing a book about the experience.