Not so easy though as WFP is paid per household in which individuals may have different marginal rates or one or other have no income tax liability at all.
This was one of the arguments against withdrawing WFP from those with high incomes:
It’s worth reading the closing paragraphs of:
researchbriefings.files.parliament.uk/documents/SN06019/SN06019.pdf
It has been suggested that the Winter Fuel Payment should be withdrawn from higher income pensioners, but it is not always clear what income threshold proponents have in mind. The Winter Fuel Payment could be withdrawn from those paying higher rate income tax, but relatively few Winter Fuel Payment recipients are higher (or additional) rate taxpayers.
Whatever the income/wealth threshold chosen, there is the question of how would identify those affected each year. In addition, one would have to decide whether income/wealth should be measured on an individual or household basis. Looking at income/wealth in an individual basis could result in, for example, partners of millionaires who have no income themselves receiving a Winter Fuel Payment. Basing entitlement on household income might be seen as fairer, but could involve introducing a complicated and expensive means-test, reducing the savings from the measure.
Withdrawal at a certain threshold would also create a “cliff-edge” problem. This could be tackled by introducing some sort to “taper”, as has been done for the Child Benefit High Income Charge, but this could be complicated and expensive to administer.
It’s worth reading the whole paper. If more people did they would have a better understanding of why it was left as it was for 27 years and should have remained that way.
I'm not saying there isn't a way to claw back WFP from people with high(er) incomes. Most will file a tax return and require an end of year assessment so it would be easy to do but it's debateable whether the tax recovered would exceed the overall benefits of spending the £200 in the economy. Most people would pay an extra £40 tax - precisely the same as spending £200 on something that attracts 20% VAT.
It would be so much easier to pay it universally in the first instance and let people spend it how they chose.