Owe tax?

spidereyes

I've just got home to find a letter from hmrc with my tax code for the next year, dramatically reduced stating I owe the best part of £509 in tax!

I've been in full time employment for the past 2 years and have genuinely no idea how they've worked this out.


Last year I changed jobs, when I started my new job I ended up paying a shed load of tax extra (like an extra £94 a month) for the first few months. I asked my payroll department a they said it was due to a overlap between changing jobs and it would work itself out.

I have paid sufficent tax for this tax year based on my earnings.

The only thing I can think of is that I owe it for 2 years ago? There was a short period where I was temping, the agency never took tax off me - I assumed this was cos I only earnt about 2k through them.


Is it possible I'm being chased for something from 2 years ago?
Why would this never have one to light before?


Based on the new tax code I've been put on its going to take 3-4 years to pay off the amount I apparently owe (paying an extra £15 a month tax)

Any ideas?