Hi Takver and HEG
Yes, I do think that, on the whole, HMRC to a pretty good job collecting taxes. Particularly given the limited resources they have.
You asked what the UK could do to raise more tax as a mechanism to increase net income equality, which I think has within it the implicit assumption that we need to tax the rich more to pay for more benefits.
Personally, I think the first step to increasing equality has nothing to do with taxation; we need to do something to decrease the wage disparity between how much the average work gets paid compared to the highest paid worker (usually director) of a company.
In the UK, the ratio is around 15 across all companies (that is, the highest paid worker gets paid 15 times more than the average for a worker in his company). It used to be lower - a ratio of 10 was more common 20 odd years ago, but even then was much higher than the average for the developing world of around 5. Only the US consistently maintains a higher ratio - theirs is around 20.
Various experts on boardroom pay have suggested that executive remuneration should be capped at a multiple (usually 5) of the average salary for the company, and I support this. It would stop bosses being awarded 10% payrises plus share options, whilst employees get pay freezes. And I don't for one moment believe the self-serving guff from execs that limiting exec pay would create a brain drain;if they're so great they can sod off to the US and see how long it takes them to find a directorship there.
Turning to your specific question on raising taxes. I know this is controversial, but I wouldnt do very much at the moment. I think the squeeze on spending caused by any tax rises would do more harm than can be justified by the revenue raised.
The problem is that the country's debts are SO large that all tax raising measures are really just tinkering around the edges. Our only hope is to stimulate economic growth, which has two benefits. First it allows the debt to be repaid more quickly. And secondly, it shrinks the size of the debt relative to GDP.
I hate the current benefit cuts, which I think go too far and are preventing economic growth. But as a nation we have to accept we were living beyond our means and some cuts are necessary to maintain the UK's credit rating.
Long term, I would maintain VAT at 20% (still below the European avergage) whilst making sure that vital expenditure (rent/mortgage, food, childrens' clothes, utiliies) are exempt from VAT. The poorest parts of our population pay out a much greater percentage of their income on vital expentiture than the rest of us, and so it's critical that they don't pay VAT as well.
I might raise NIC for companies by a further 1%. That would raise another £15bn per annum. But I would worry that it would be at the expense of private pension provision.
I might keep taxing banks' payrolls for bonuses. That's another £5bn.
I don't think we'll see tax deductions for childcare in a month of SUndays.