You can go non-tax status from the day you leave the UK by completing a Form P85. This means that you are not liable to pay tax from the day you leave the UK. On permanent return to the UK you complete a Form P86 which renders you liable for tax form the day you return. Not to re-register is an offence.

However there are certain basic rules.

You are allowed back to the UK for a maximum of 186 days in a single year or an average of 91 days per year over 3 years. You must also be out of the UK for a single full tax year (6Apr to 5Apr) before returning to the UK permanently otherwise you will be liable for tax on any earnings.

This is the thrust of it but there are other rules regarding qualifying criteria for NT status in the first place. All the information you need is on the HMRC website.

The tax office that deals with ex-pats is located in Salford Nr Manchester and I have always found them very helpful for advice by email or telephone.

If you want the direct dial number send me a private message here and I will send you it.

As a side note you should make arrangements with the NI contributions office to maintain your right to UK National Pension and use of NHS etc. Details of how to do this are on the HMRC website.