摘要：语义上，它们相当于not after，但not放在主动词前-助动词后，语感通常更顺一些。因此，将上面两句的no later than换成not after, 语义勉强说的过去，但语感不好。

not/no later than含义是“不迟于”某特定时刻，如

【例句1】Please arrive no later than 8 o'clock. (请不晚于8点钟到达。)[牛津高级学者辞典]

【例句2】The recession should be over no later than spring. (经济衰退应不迟于春季结束。) [剑桥高级学者辞典]

语义上，它们相当于not after，但not放在主动词前-助动词后，语感通常更顺一些。因此，将上面两句的no later than换成not after, 语义勉强说的过去，但语感不好。

no相当于not any，也就是语气更强。更强语气一是适合非正式表达，二是使用频度会比较高。

按https://www.britannica.com/的Ask the Editor的说法：

1. no later than和not later than都用于表达当某事件或行动应该或必须在某时间节点前(含)完成；

2. no later than比not later than更流行；

3. not later多用于正式的公告或通知中。

再品读例句：

【例句3】She said she'd prefer us to arrive no later than nine o'clock. (她说她希望我们不迟于九点钟到达。)[剑桥高级学者辞典]

【例句4】You must complete the forms as soon as possible, but no later than July 11th. (您必须尽快填写表格，但不得迟于7月11日。)[剑桥高级学者辞典]

【例句5】A notice must be issued not later than 60 days before the election. （通知必须在选举前60天内发出。 ）[剑桥高级学者辞典]

【例句6】Please be in the meeting hall not later than 18:30. (请在18:30之前到会议厅。) [剑桥高级学者辞典]

来源：小蜗牛的梦