Yes, and the flip side of this is that unemployed families have no incentive to get a job because the net gain (after tax/benefits reduction) would be trivial. This creates a divide between 2 earner households and no earner households - the UK has the highest rate of jobless households in the EU, despite having lower than average unemployment.
The reason for this anomaly is down to the way the tax & benefits systems work - benefits and tax credits are withdrawn sharply at the lower end which acts as a disincentive for the first earner, while independant taxation makes it very worthwhile for the second earner to get a job.
In other countries where taxation is assessed on families not individuals, there is far fairer spread of jobs and as a consequence less is needed for benefits.
The benefits reforms this government are proposing look excellent - the universal credit and single "reasonable" withdrawal rate should simplify the current mess and act as an incentive to work, but unless they combine it with a reform of the tax system it probably won't work, as second earners will still have a far larger gain to work than first earners.
Unfortunately independant taxation seems to be some sort of sacred cow which nobody dares challenge. Or rather politicials have pretended it is.