Why would someone use a wrong birthdate despite knowing his correct one?

[Marmalady]

My Grandfather's elder brother Edward William Wainwright was born on 16th Sept 1879 -- I have his birth certificate to prove this.

He was not baptised as a baby, but as a teenager in May 1896. Here his birthdate is given as 23rd Sept 1880 -- a year and a week later!

This confusion of birthdates continued into later life. In 1911, when he would be in his early 30s, he travels from Germany into Belgium. On his entry documents, he originally gives his birthdate as 23 Sept 1880, but this is crossed out and 16 Sept 1879 written in a different hand

Can anyone think of any reason for the use of two birthdates like this?
I have ruled out the death of a 1879 baby and ensuing re-use of names for a 1880 baby.

[*Sandra*]

People back then had such poor literacy skills - they really didn't know their age/DOB and just guessed. It was quite common for dates to be incorrect.

Sandra

[nanny jan]

My grandfather, born 1880, was always muddled about his birthdate .....1939 Register is completely wrong....no wonder he was surprised to get his old age pension.....he was a year out!

[iluleah]

Birthdays were not celebrated and many families had many children so remembering their ages was not so important as it would be now where everyone has to be documented on everything.
Likely he really didn't know his birth date, possible was told different dates at different times.

[Gadget]

I would have thought that the reason in this case was what you've said - the discrepancy between the baptism date and the birth registration date. (add- the different hand had had sight of the birth cert)

My father was perfectly  literate but always gave his DofB as a year later that it was - except when he got to 80 

[tellx]

If he was the eldest child, was he born "a bit too soon" after his parents wedding?

My Great Aunt always claimed to be a year younger than she was for this reason. When official documents were needed (ie passport etc) the real age had to be used.

[aghadowey]

I'm having trouble understanding the title of this thread Why would someone use a wrong birthdate despite knowing his correct one?

Why do you think that he knew his birthdate? Just because there's a birth registration for a particular date doesn't mean that he either knew the date of had a copy of his certificate.

It could be that there was an earlier child with the same name who died and his birth didn't actually get registered, etc.

My father-in-law was born before WWI and never remembered his exact birthdate even though his date of birth is on his birth certificate, in baptismal register, school roll book, etc. If he really, really, really needed the exact date them the birth certificate was produced but that was only in later years when he had to fill out official forms.

[groom]

If he was the eldest child, was he born "a bit too soon" after his parents wedding?

My Great Aunt always claimed to be a year younger than she was for this reason.

That was the very reason my grandmother claimed to be a year younger. It was pure luck that my uncle found her birth certificate before he registered her death when she died aged nearly  99 - although everyone thought she was 98. I often wonder if she would have admitted it if she'd reached 100, or whether after all those years she'd really forgotten how old she was.

[Marmalady]

He was the second child of the family -- so the "too soon after the wedding" does not apply

He was also literate & numerate -- in 1901 he was a Wages Clerk, but whilst travelling around Europe
he was a teacher of English

I presumed he would know of his correct birthdate -- or at least have a passport / documents with the correct date -- who else in Antwerp would have access to records to have the date on his Belgian entry papers corrected?