NI on "one-off" earnings

Would it be as an employee or self-employed?

If you can treat it as self-employment, you'd need to pay the 2.10 / week class 2 NI, but no Class 4 NI until total s/e profits reach nearly 5k in the year.

If you become employed, complete job in one month and get one pay slip, then NI will work out at 175 on 2k (ie just under 9%)

NI is only considered on an annual basis if you're a director or exceed the annual maximum NIC.

Slightly OT - re. CTC - the whole idea is to make it more worth while for lower-paid people to take a job. So it's inevitable that the effective tax rate (if you regard loss of CTC as a tax) will be high. Many brains have spent many decades trying to resolve that one!!

Self-employed. Sorry, forgot to say.

Ok, thanks for that.

Unsuccessfully ;-) I think you'd have to agree, though, that 70% is pretty penal. (Actually, it turns out I had misinterpreted the very confusing CTC/WTC system. I may not lose CTC for a while as the threshold is higher than I'd thought. And they've lost one of my kids.)

Yeah right. Most other first world countries resolved it decades ago. You give decent tax allowances which reflect the needs of the family - then you don't need over complicated and bureacratic tax credits. You encourage work, because tax allowances are no use unless you earn enough to use them. You only assess income once, not twice or even three times like here. The marginal rate of taxation for a family is not 70% up to around 24,000 for a family with 2 kids, or 70% to well over 30,000 for a family with 4 kids. Tax for employees is collected via a PAYE system, so is automatically adjusted as income changes.

Obviously benefits are still be required for those out of work or on very low pay - but you take the vast majority out of the benefits system by not overtaxing them.

Here a family of 4 on 20,000 earn easily enough to support themselves, but they have to go through the farce of being taxed much more than they can afford, and then claiming most of that tax back in tax credits, child benefit, and possibly housing benefit.

The flaw in this is UK governments have been obsessed with getting the basic rate of income tax as low as possible, because they think people are stupid enough to think that low tax rates mean low taxes. Having decent tax allowances would require tax rates to be raised. Overall people would be better off as the costly and incompetant bureacracy associated with tax credits would be eliminated, and also less people would clog up the benefits system.

Yup. And it goes up to 95.5% if you're claiming housing benefit and council tax benefit! It can go to over 100% if you're claiming ISMI (mortgage interest).

If you're working the reduction applies to the total of the WTC and CTC. It reduces WTC first, then once WTC is reduced to zero it starts reducing the CTC. Except for the last 545 of the CTC which remains till income reaches 50,000 and is then reduced at 6.666666666666666666666667%. And the first 2,500 you earn over and above last year's earnings doesn't reduce WTC/CTC at all. And the first 300 of bank interest doesn't count. And SMP/SPP don't count. Tax free income doesn't count (eg ISA's). Other taxable income does, mostly. What's so confusing about that?