Amortisation of know-how: lump sum payments deductible over a staged multi year schedule, accelerated for research developed know how. Section 35AB provides specified amortisation rules for lump sum payments for acquiring know-how: generally one sixth deductible in the year of payment with the balance amortised in equal instalments over the next five years; where the know how is developed in an eligible laboratory, university or institution, one third is deductible in the year of payment with the balance amortised in equal instalments over the next two years. The section defines know-how as industrial information or techniques aiding manufacture, processing or resource exploitation.