Hello and welcome to the site. Thank you for your question. You can pay the tax bill in instalments but you should be aware of interest and penalties if you don't pay your tax on time. As you propose to clear your tax bill for 2012-13 now, you should concern yourself with interest charges for late payment of 1st instalment for tax year 2013-14 only. As it is your intention to clear it in 5 monthly instalments, the charge should not be significant. Interest is charged at 3%pa on balance outstanding. More information on interest and penalties if you don't pay your tax on time can be found here
I hope this is helpful and answers your question.
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