According to Sky News, Tesco Bank is in negotiations with the regulator and is hoping for a "substantially lower" fine, which is expected to be agreed in the next few weeks.
If imposed at £30m, the fine would be the largest ever seen in relation to cyber crime.
In November 2016, Tesco Bank suspended all online transactions after an attempted data breach.
It was initially feared that up to 40,000 customers may have had their accounts compromised, however this was later revised down to under 50 victims, all of which were reimbursed for monetary losses.
Tesco eventually compensated 9,000 customers a total of £2.5m, but insisted that no customer data was compromised in the 'highly sophisticated' attack.
Industry analysts have raised concerns about the size of the FCA fine, considering the 'limited' extent of the Tesco Bank breach and compared to the £500,000 penalty Equifax received over its large-scale data breach last year, in which the personal information of up to 400,000 UK customers was potentially accessed.
