Companies can attach up to 28 cents of imputation credit to each $1 of gross dividend they pay. This maximum imputation ratio makes sure that the imputation credits attached to a dividend are not more than the tax that was paid on the profits the dividend came from.
The maximum imputation ratio is written using the format ‘28:72’. This shows that 28 cents of credit are attached to each 72 cents of profit. This is the same as attaching 38.89 cents of imputation credit to each $1 share of net profit after tax.