COPE explained
The headline
COPE stands for Contracted-Out Pension Equivalent. It is the value of the additional State Pension you would have built up if you had not been contracted out, expressed as a weekly figure1. The DWP shows your personal COPE figure on your State Pension forecast.
Why it reduces the headline
Under the transition rules, your starting amount in April 2016 was the higher of two calculations: a new-SP-style figure that subtracted COPE, and a basic-SP-plus-additional-pension figure2. For many contracted-out workers the new-style figure (after COPE) is lower, but the higher of the two still shows below the £241.30 headline because the additional-pension stack itself was reduced by contracting out.
Does COPE reduce actual income?
Not directly. COPE is a notional figure; the actual money it represents was paid into your workplace or personal pension during the contracted-out years. So your retirement income is State Pension (post COPE) plus the workplace pension that received the contracting-out rebate. Whether that combination is higher or lower than the full new SP depends on the investment performance of that workplace scheme3.
Will Class 3 close the COPE gap?
Sometimes yes, often partially. Each post-April-2016 qualifying year you add (paid or voluntary) lifts your new-SP figure by about £6.89/wk until it hits the £241.30 cap. If your COPE gap is, say, £20/wk and you have 3 future years to add, you can close it. If the gap is larger than the remaining ceiling, you cannot.