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21st of march 2021 or ASAP AFTER THAT
well that's what mine says anyway
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I deliberately filled out my parents census early and I added a note in the comments box at the end saying that I couldn't give a shit about it being early, it had to be done when we were visiting as they don't have broadband. The form states that it should be completed as per the dates above or face a fine of £1000 but both of my parents are disabled, and I have better things to be doing with my time with them without wasting my time on gender related forms. It says that if you are unable to complete the form, get your partner to do it. Well no shit, they are both disabled so how does that work. It also assumes that everybody has the Internet and a computer, which they don't. You can request a paper copy but it warns that you'll be wasting tax payers money if you do.
I declined the ethnicity, religion, work status and many other questions relating to gender, or are you the same gender that you were born. When I put my dad's date of birth, the next page said "So you are 91, are you actively seeking work, in work or long term sick". Well, this may shock them but no he's not actively seeking work.