Tynwald will be asked this month to approve a hike in the sewerage rate.
The sewerage rate was introduced in April this year to replace the £50 flat rate toilet tax, deemed by many to be inequitable, with even Chief Minister Allan Bell accepting it was unfair.
For 2015-16 the rate was set at 62p in the pound, raising the equivalent sum to the toilet tax if it had been increased to £100 as planned.
But Manx Utilities Authority chairman Alfred Cannan MHK will seek Tynwald approval this month to increase the sewerage rate by a further 30p to 92p in the pound for 2016-17.
The MUA said the increase is in line with its 20-year financial plan and reflects the continuing scheduled withdrawal of the Treasury subsidy.
Mr Cannan has said the MUA will continue to review the charging regime and options for having a part fixed fee and part rates charge could be considered as further funding from Treasury is withdrawn.