What is a 'Retained Margin'?
There is often confusion between the differences of a Cost Plus Margin and a Retained Margin.

'Cost Plus' is simply the cost price plus the percentage of the cost price.

'Retained Margin' means how much profit gained in a sale price.

For example:

Cost Price: £100
Sale Price: £125

Cost Plus = Cost (£100) plus 25% of cost price (£25)
Retained Margin = profit of £25 on a sale of £125 ie 25/125 = 20%