I paid a tax bill today, my ‘payment on account’.  For those doing a self assessment tax return, HMRC requires two payments per year and the payment on account is supposed to be a helpful way for the self employed to spread income tax payments.  For the payment on account HMRC guesses how much tax you’ll pay in the tax year (based on what you paid last tax year) and halves it, and that is what you have to give them in advance.  Six months later you pay the balance.

So this is relevant to my pregnancy because I’m going to take time off from working from sometime after May 2014 to an unspecified later date.  This will reduce my income for the 2014/15 tax year, which will reduce the amount of income tax I need to pay.

Therefore, when HMRC are estimating my income for the next tax year they’ll get it wrong.  At some point I’ll have to tell them that or they will start demanding money from me that I don’t have (and in fact won’t owe them).

So paying my tax bill this time prompted me to look into this a bit and so far as I can see HMRC will do the estimating for 2014/14 next December so I’ll have to notify them of my changed circumstances well before then.  There’s a form.  Or you can ring them.  Looks like you have to tell them what you expect to earn in the year, so it makes sense to wait and see when I start maternity leave first and go from there.  Complicated.