There is a letter in Hanyu Pinyin that a Chinese passport will not print. It is ü, and only four syllables in the whole language carry it: lü, nü, lüe and nüe. If your surname is 吕, or 律, or 绿, or 闾, this is your problem and almost nobody else's.
The single letter is replaced by two different rules, which is how a family can end up with documents that disagree on the spelling of their own name.
What the immigration authority actually says
The operative text is short enough to quote in full. From the National Immigration Administration's announcement of 29 September 2021:
LÜ（吕等字）、NÜ（女等字）中的字母"Ü"应当转换为"YU"；LÜE（略等字）、NÜE（虐等字）中的字母"Ü"应当转换为"U"。
In English: in lü and nü, ü becomes YU. In lüe and nüe, ü becomes U.
So 吕 is printed LYU and 女 is NYU, but 略 is LUE and 虐 is NUE. Syllables ending in -e take a bare u. The logic isn't obvious from the outside, but it doesn't have to be; it's what the machine-readable zone requires and what the printer produces.
⚠️ Nearly every romanisation tool gets this wrong, ours included until we wrote this guide. The easy assumption is a single substitution — ü becomes yu, everywhere — and it produces LYUE and NYUE, which appear on no Chinese passport at all. Getting 吕 right and 略 wrong looks like success, because 吕 is the surname people test with.
Two authorities, and they do not agree on how binding this is
There is also a national standard: GB/T 28039-2011, the spelling rules for Chinese personal names in pinyin, in force since 1 February 2012. Its clause 6.2 addresses the same problem and gives the same headline answer, with its own worked example — 吕和平 becomes LYU HEPING.
But it says 可以: Ü may be replaced by YU. The immigration announcement says 应当: it shall be. And the standard does not carve out the -üe syllables at all.
That gap matters more than it looks. A standard that permits produces variation; an instruction that mandates produces uniformity. The nine years between the two documents are exactly the period in which people's documents drifted apart, and anyone citing only the standard — as most explanations do — is describing a weaker rule than the one being applied at the counter.
The spelling before this one was LV, and it was not a mistake
Older documents print LV, which looks like a typo but isn't.
On a pinyin input method, v is the key you press to get ü — the letter is unused in pinyin otherwise, so it was free to borrow. When a system that could not store ü had to store something, v was the character already standing in for it everywhere else. LV is a keyboard convention that hardened into print.
A single household can therefore hold three documents with three spellings of one surname — an older passport reading LV, a newer one reading LYU, and a bank record still carrying LÜ from a form typed by hand.
The clause that almost nobody mentions
The 2021 announcement has a second clause, and it is the practically useful half:
考虑到一些内地居民仍持用按旧规则打印制作的出入境证件……国家移民管理机构可以根据申请人要求，在签发新的出入境证件时打印与申请人原有出入境证件一致的拼音姓名。
Because some residents still hold documents printed under the old rules, the authority may, at the applicant's request, print the pinyin name matching their existing document — precisely so that new and old documents do not disagree.
This inverts the usual advice. You are not obliged to accept the current spelling on a renewal. If your degree certificate, your visa history, your property title and your bank accounts all say LV, the consistent choice may be to ask for LV again. A passport that disagrees with your other documents is a worse outcome than a passport that disagrees with the current rule, and the rule itself says so.
It is a may, not a right — the wording is 可以根据申请人要求 — so it is a request that can be refused, and it must be made at application time rather than argued afterwards.
Why this hits four families and nobody else
The scale of this is worth stating plainly, because it is easy to write about ü as though it were a general problem with Chinese names. It is not. Every other syllable that sounds like it might carry a diaeresis has already lost it in ordinary pinyin: after j, q, x and y the ü is written as a plain u, so 徐 is Xu, 居 is Ju and 曲 is Qu, and none of them go anywhere near this rule.
What remains is l and n. That is the whole population: 吕, 律, 绿, 闾 and their relatives on the surname side, and 女 and 略 for anyone whose given name uses them — the first printing NYU, the second LUE, which is the pair most tools get half right.
⚠️ And the neighbouring surname must not be swept up with them. 卢 is lu with a plain u and is printed LU. 吕 is lü and is printed LYU. They are different families, and a converter that strips diaeresis marks before applying the rule merges them into one — which is the failure mode that would actually cost somebody a boarding pass.
What to do with this
If you are filling in a form: use the spelling that is on the document the form will be checked against, not the spelling a converter gives you. If those differ, the document wins every time.
If you are renewing: decide before you apply whether you want consistency with your old documents or with the current rule, and if it is the former, ask under clause 2 at the counter.
If you are building software that stores names: store what the document says, not what your library computes. Our Chinese name romanizer now applies both halves of the immigration rule and shows the same name across Hanyu Pinyin, Wade–Giles, Tongyong and Cantonese side by side, because a name has more than one correct spelling depending on which authority is asking. If you want the underlying reading rather than a document spelling, our pinyin converter keeps the ü where ordinary pinyin keeps it — which is the right answer for a dictionary and the wrong one for a passport.
Where this comes from, and what will date it
The two quoted clauses were read from the National Immigration Administration's own announcement of 29 September 2021, not from press coverage of it. GB/T 28039-2011's date, status and clause 6.2 worked example are from the standard's registry record and a transcription of its text; we have flagged that the clause wording itself was read from a transcription rather than the issuing body's PDF, which is why the immigration announcement rather than the standard is the source for every operative claim above.
We deliberately do not state a fee or a form number for the clause 2 request. Reports of how that is handled in practice are secondary and several years old, and a stale number attached to a government procedure is worse than no number.
This guide dates if the immigration authority reissues the printing rule, or if GB/T 28039-2011 is revised to match it. The second would be the quieter change and the more useful one, because the gap between may and shall is what this whole situation is made of.
