Regret letter for not sending quotation

The way you deal with mistakes is often more important to keep a good business relation, than making them. Consider solving issues caused by you as one of the most important tasks you have. Solving and providing enough service when an issue occurs, always deserves your utmost attention. Therefore, communicating in a professional manner will get you respect and will bring you further.

How do you write a late submission or regret letter for not sending quotation?

In business, people depend on each other's agreements and are keen on meeting the deadlines. A deadline in work submission can be vital. Therefore, it's important to notify the other party, if any delay occurs, since a lot of work can depend on the submission of the work required. This mostly applies to commercial companies that depend on money coming in from sales, and on fluctuations in the market. If you are in such a situation, make sure to notify the other party about the delay. There is no need to panic (yet), since you can manage expectations in time or even fix the situation by writing an apology letter. In your apology letter, explain why you have to delay the document submission. 
This should be done in a professional way. The note should also be simple and straight forward. Since communication is a key thing to understanding someone, your boss will end up not judging. While writing this letter, consider the following points:

1. Begin explaining the reason for the delay or the mistake why you were not able to submit the quotation or assignment.
2. Use the actual date you were supposed to submit the document.
3. Provide a genuine explanation why you failed to do so.
4. Consider any potential damage that was caused in the business because of late submission.
5. Mention that you are responsible for the damage that resulted from this fault.
   
6. Ensure the other party of the new date you will submit the quotation.
7. Repeat this issue will not happen again by indicating that you have taken the necessary measures.
   
8. Provide an apology, mention you deeply regret letting the party down.
9. Consider referring to measures you have put in place to ease the damage already caused, like providing a rough quote or exclude some of the costs;
10. Always start and end your letter with a salutation.
    
11. Finally, hope for a good positive consideration and it may strengthen the business relationship.
    

If you wish to write a letter to about apologizing for the late submission of quotations or documents, please have a look at this sample:

Subject: {{Subject}}

Dear Sir/Madam {{Name}},

Please accept my sincere apologies for the delay in sending the quotation that you asked for.

I try to always respond to my customer's queries in a timely fashion, but sometimes unexpected hurdles come across my path.

Enclosed with this letter is the quote that you requested for.

Thank you very much for your patience and understanding.

Yours sincerely,

{{Signature}}

{{Formal Name}} {{Title}}

Using Sample Apology Letter for being late in submission, as a guide it can make things clearer, easier, and simpler. Check out this sample regret letter for not sending quotation directly.