Bert Lance, the Georgia banker who held a key post in the Carter administration, yesterday agreed to an order that prevents him from becoming an official of a federally insured bank without prior consent of the government.

Lance, who was director of the Office of Management and Budget in the Carter administration, also agreed to pay a $50,000 fine as part of a settlement of a lawsuit and administrative actions brought against him by the Office of the Comptroller of the Currency, the federal agency that regulates nationally chartered banks.

The comptroller's office charged that Lance, violated federal securities laws and made questionable loans to himself, his family and his friends while chairman of Calhoun (Ga.) First National Bank. The agency also accused Lance of check-kiting, or overdrafting a bank account, and said Lance received proceeds from credit life insurance sales that should have gone to the Calhoun bank itself.

Despite the comptroller's charges, filed last summer, Lance won reelection as chairman of the bank last month, only to resign two weeks later and announce that he would sell his 14.75 percent interest in the institution.

The bank agreed to limit its lending to Lance, to restrict his checking-account activity and to change the company that writes its credit life insurance within 60 days. The bank also agreed to cease any violations of securities laws and to file amended disclosure statements to the comptroller's office. Many of the activities the comptroller alleged Lance engaged in as head of Calhoun should be reported under federal securities laws.

Lance also agreed to the dismissal of a suit he filed against the comptroller's office, alleging the agency violated his right to privacy by leaking details of a report on its investigation. Lance and the bank originally filed the suit after details of the comptroller's report appeared in The Atlanta Constitution last summer. But the bank withdrew from the suit when an FBI investigation established that the comptroller did not leak the information.

Lance resigned under pressure as OMB director in 1978 after allegations that he violated banking laws before joining the Carter administration. A federal jury found Lance not guilty of those charges.

But the federal banking agency began another investigation of Lance several years ago after a former vice president and a former board member of the bank reported to the comptroller's office possible irregularities in behavior by Lance and the Calhoun bank.

The vice president, Robert Morast, was fired and has since sued Lance, Lance's son David and the bank, seeking $8.3 million in damages. The director, Marvin Taylor, was voted out of office in November 1984.