Ok, in my circumstances I work on an oil platform in the UK sector of the Continental Shelf if i were to have my home in Spain if my wife were to live in that home and my daughter attended school in Spain I would be classed as resident in Spain due to the double taxation treaty. As I would have to continue paying class 1 NICS in the UK the UK is therefore the competent state responsible for national health care costs. As you say the E106 is soley a "certificate of entitlement to sickness and maternity insurance benefits in kind for persons residing in a country other than the competent country" therefore if you have an E106 it is proof that you are paying NICS or have done until fairly recently so could be used in the absence of any other proof. Incidentaly if you are currently in employment in the UK the E106 is issued by HMRC otherwise by DWP.
Regulations EC No. 1408/71 and 574/72 govern the various rules for benefits and health entitlements and "Regulation 1408/71 allows for reimbursement of costs for certain types of cross-border
care. Frontier workers benefit from a double access to health care, both in the state of residence and in the state of work." Because of this regulation I think that is why the nhs website states "If you have a valid E106, you can still access NHS healthcare." here
Living abroad
and also here
Healthcare in Spain I emailed the dept of health to clarify this statement and this was the reply:
Thank you for your email of 10 June to the Department of Health about the form E106.
The NHS remains responsible for the healthcare of the holder of a form E106. Therefore if you wish to return to the UK specifically for treatment you can directly contact a hospital to arrange treatment.
In order to cover yourself for unplanned treatment on a trip to the UK, you will need to carry a Spanish issued European Health Insurance Card (EHIC).
To find out more about the form E106 please contact the Department for Work and Pensions (DWP) which is responsible for issuing the form:
Department for Work and Pensions (DWP)
The Pensions Service
Tyneview Park
Whitley Road
Newcastle upon Tyne
NE98 1BA
Tel: 0191 218 7777
I hope this information has been of help.
Yours sincerely,
With reference to the EHIC in their answer I think that they are talking about the situation of say an early retiree who has an E106 issued by the DWP and actually think that in the case of an HMRC issued E106 because of ongoing NICS the holder would actually be entitled to a UK issued EHIC.
My situation is fairly unusual in the fact that i would be working on the UK Continental Shelf, however i think there could be similar circumstances whereby if some-one were to move to Spain yet travel back to the uk regularly for employment or self-employment and to have no earnings in Spain that they could be classed a Spanish tax resident due to the double taxation treaty yet as they would be paying UK NICS the UK would be the competent state responsible for their health care payments and could be why the original poster was initially advised to carry on paying UK Tax/NICS.