Interest on delayed tax payments requires self payment from the day after due; excess input credit claims incur higher notified interest. Failure to pay tax within the prescribed period attracts self assessed interest for the period of default, at a Government notified rate subject to the statutory cap, calculated in the prescribed manner from the day after the tax was due. Undue or excess input tax credit claims, or undue reductions in output tax liability, attract interest on the excess amount at a Government notified rate (subject to the statutory cap) under the Act.