The fine rate for overstay in Indonesia is IDR 1,000,000 per day.
To avoid overstay, you should often remember and pay attention to the validity period of your visa, and immediately apply for a visa extension to the local immigration office no later than 7 days before the visa expires. You can do this is if your type of visa is a type of B 211 visit visa, and if your visa is a type of residence visa/KITAS, then you must apply for an extension 1 month before expiration or 2 months before expiration if your visa is a Work Visa/KITAS (Index 312).