PolicyEngine is showing a 116% marginal tax rate starting at about £16,000, with varying employment-income-width. All these examples have only employment income.
One adult, one child:

Two parents, one child:

Two parents, two children:

Looks OK for a couple with no children:

PolicyEngine is showing a 116% marginal tax rate starting at about £16,000, with varying employment-income-width. All these examples have only employment income.
One adult, one child:
Two parents, one child:

Two parents, two children:

Looks OK for a couple with no children:
