The Government Census questionnaire sent out this month could potentially neglect Welsh speakers who live in England.
One question was left blank on the 2011 Census distributed in England this March, as this enquired whether residents could read, write and understand Welsh.
Only questionnaires sent out in Wales included a question on the Welsh language.
With about 150,000 Welsh speakers currently living in England, this choice by the Office of National Statistics has been questioned.
Gruff Jones, a Welsh speaker currently living in England, said: "I think it is a bad decision. It seems disingenuous by the people who sent the census out.
"It is playing into the hands of the absolute devolution idea. It separates everyone.
"It feels like now the Welsh Assembly Government has its own powers, we are just left to our own devices. But it is much more complicated than that."
There is still a question on the Census (numbered 18), which follows the blank question, asking residents to list their mother tongue.
A spokeswoman for the Office of National Statistics said: "A lot of work goes into looking at the questions. It was not deemed necessary to have that question on the English questionnaires.
Plaid Cymru have also backed the decision not to include the Welsh language question on the Census forms sent out in England.
A spokesperson for Plaid said: "Although there are many Welsh-speakers in England and it may be of interest to discover the numbers of welsh speakers there, it is unlikely that the inclusion of this question for English households would be of immediate importance."