Son ödeme tarihini kaçırmayın; aksi takdirde gecikme zammı uygulanır.

It is a noun phrase meaning due date or more literally final payment date.

Breakdown:

• son = last, final
• ödeme = payment
• tarihi = its date / date of

A very common Turkish pattern is the noun compound:

• ödeme tarihi = payment date

In this structure, the second noun often takes a possessive-looking ending, even though English does not translate it as possession. So ödeme tarihi is the normal way to say payment date.

Then son is added in front:

• son ödeme tarihi = final payment date / due date

Because the phrase is the definite direct object of kaçırmayın.

Here is the structure:

• son ödeme tarihi = the due date
• son ödeme tarihini = the due date, marked as a definite object

Turkish often adds the accusative ending to a definite direct object. Since tarihi already ends with a possessive-type suffix, the accusative appears as -ni:

• tarihi
  • accusative → tarihini

That n is a buffer consonant.

So:

• Son ödeme tarihini kaçırmayın = Don’t miss the due date

Turkish does not have a direct equivalent of the English article the.

Instead, definiteness is often shown by:

• context
• word order
• the accusative ending on direct objects

So in this sentence, tarihini already tells you we are talking about a specific, definite date: the due date.

That is why Turkish does not need a separate word like the here.

Kaçırmayın is a negative imperative: don’t miss.

It can be used for:

• you all don’t miss...
• you don’t miss... in a polite/formal way

Breakdown:

• kaçırmak = to miss
• -ma- = negation
• -(y)ın = plural/polite imperative ending

So:

• kaçırın = miss!
• kaçırmayın = don’t miss!

In public notices, instructions, and customer messages, this form is very common because it sounds polite and appropriate.

Here, kaçırmak means to miss in the sense of failing to catch, meet, or make use of something.

Common examples:

• otobüsü kaçırmak = to miss the bus
• fırsatı kaçırmak = to miss the opportunity
• son tarihi kaçırmak = to miss the deadline

So in this sentence, it means do not fail to pay by the due date.

Even though the literal history of the verb is different, you should learn kaçırmak here as the normal Turkish verb for miss in this kind of context.

Yes.

Turkish kaçırmayın can address:

• more than one person, or
• one person politely/formally

That is why company notices, ads, SMS reminders, and official messages often use this form. It is respectful and works well for the general public.

If you were speaking casually to one friend, you would more likely say:

• kaçırma = don’t miss

But in a formal warning or reminder, kaçırmayın is much more natural.

Aksi takdirde means otherwise, if not, or if that is not the case.

It is a common formal linking expression, especially in:

• notices
• contracts
• bank messages
• official warnings
• instructions

So this sentence is structured like:

• Don’t miss the due date; otherwise...

In everyday speech, people may use other expressions, but aksi takdirde is very typical in written formal Turkish.

Gecikme zammı is a formal financial term meaning something like:

• late fee
• late-payment surcharge
• penalty increase
• sometimes default interest, depending on context

Breakdown:

• gecikme = delay, lateness
• zammı = surcharge / increase / added amount

So the whole phrase refers to an extra amount charged because payment was late.

A small spelling point: the base word is zam, but in this form it appears as zammı. Some Turkish words double the final consonant when a vowel-initial suffix is added, and this is one of those cases.

Uygulanır is the passive aorist form of uygulamak.

Breakdown:

• uygulamak = to apply, implement
• uygulanmak = to be applied
• uygulanır = is applied / gets applied / will be applied

So:

• gecikme zammı uygulanır = a late fee is applied

The passive is very common in formal Turkish because the sentence focuses on the rule or result, not on who does it.

English often says:

• a late fee will be charged
• a late fee applies

Turkish expresses that idea with uygulanır.

Because in Turkish, the aorist is often used for:

• general truths
• rules
• procedures
• automatic consequences

So uygulanır does not just mean is applied right now. In formal contexts, it often means:

• is applied
• will be applied
• applies

This is especially common in regulations and warnings.

So the sentence means something like:

• If you miss the due date, a late fee will be applied

even though Turkish uses uygulanır, not a future-tense form.

The semicolon separates two closely connected parts:

1. Son ödeme tarihini kaçırmayın
2. aksi takdirde gecikme zammı uygulanır

It works like:

• Don’t miss the due date; otherwise, a late fee will be applied.

In Turkish formal writing, this punctuation is normal when the second clause gives the consequence of the first. A period or sometimes a comma could also appear in other contexts, but the semicolon makes the relationship especially clear and formal.