flat rate 
noun
1A charge or level of payment that is the same in all cases: clients are charged a flat rate of £250 annually [as modifier]: the flat-rate state pension...
- The campaigners reckon the Treasury should replace a tax on the weight of tobacco with a flat-rate charge per cigar.
- Different flat-rate payment schemes would also operate between land in ‘severely disadvantaged areas’ and all other land.
- At best, phone companies will be able to charge a flat-rate fee for service; at worst they will have to give voice calls away.
1.1A rate of taxation that is not progressive, but remains at the same proportion on all amounts: a tax levied at a flat rate of 7.65 per cent...
- Income arising to a non-resident employee is subject to Portuguese withholding tax at a flat rate of 25 per cent.
- Now, rumours have begun to fly that he may commit himself to a reform of the federal tax system, including the possible introduction of a flat rate of income tax.
- decollation
- decollator
- decollement
- decollement zone
- decolonise
- decolonization
- decolonize
- decolor
- decolorise
- decolorization
- decolorize
- decolour
- decommission
- decommunise
- decommunization
- decommunize
- decompensated
- decompensation
- decompilation
- decompile
- decompiler
- decomposable
- decompose
- decomposer
- prorogator