Block format is the default layout for most business letters written in English. Every element, including the date line, sits flush against the left margin with no indentation. That sounds simple. In practice, writers still place the date in the wrong position, use inconsistent punctuation, or mix block format conventions with older modified-block habits. Here's how to get it right.
Where the date line sits in block format
In a block-format business letter, the date line appears two lines below the sender's address and two lines above the inside address. The date starts at the left margin. No tabs, no centering. If your letterhead already carries the sender's address, the date line sits two lines below the last line of that letterhead.
This is where block format differs from modified block. In modified block, the date line is typically centered or aligned to the right. In full block, it's always left-aligned. Mixing the two produces a document that looks inconsistent and signals that the writer didn't choose a format deliberately.
If you're unsure how the sender's address itself should be constructed, the rules are covered in detail in how to write a business letter sender's address, which walks through every component before the date line appears.
How to write the date itself
The format depends on your intended reader. For a North American audience, the standard order is month, day, year: October 15, 2026. For most other English-speaking audiences, day, month, year is preferred: 15 October 2026. Neither format uses all-numeral dates (10/15/26 or 15/10/26) in formal correspondence. Numerals alone are ambiguous across borders and informal in register.
Write the month out in full. "Oct. 15, 2026" is acceptable in less formal contexts but looks hurried in a business letter. Spell it: October 15, 2026.
Ordinal suffixes are not used in the month-day-year format. Write October 15, not October 15th. The suffix is redundant once you have the month name present, and the cleaner form reads better.
For letters that will reach international readers, the month-name format avoids the ambiguity that numeric dates create. That's a practical reason to prefer it regardless of your primary audience. The broader rules for international date formats are worth knowing if your organisation sends correspondence across regions: date and number formats in international business writing covers the full picture.
Punctuation and spacing rules
The date line in a North American format carries one comma: between the day and the year. October 15, 2026. No comma appears between the month and the day. The day-month-year format used in British and Australian English omits the comma entirely: 15 October 2026.
Two blank lines separate the date from the inside address. Not one, not three. Two. This spacing is not decorative. It reflects the standard block-format convention and keeps the document readable at a glance.
One mistake that appears regularly: writers who carry over the date punctuation rules from running prose. In a sentence, a date can read "October 15, 2026, was the deadline." That second comma after the year is required in prose but does not appear in a standalone date line. The date line is not a sentence. It needs no terminal punctuation of any kind.
Common mistakes in block format date lines
Three errors account for most of what goes wrong.
- Wrong position. The date line appears above the sender's address, or directly below the salutation. In block format it belongs in one place: two lines below the sender's address, two lines above the inside address.
- Abbreviated months. "Oct." or "Nov." in a formal letter looks rushed. Write the full month name.
- Ordinal suffixes. "October 15th, 2026" is technically readable but not standard in formal block-format correspondence. Drop the suffix.
A fourth error, less frequent but worth naming: using the date of drafting when the letter won't be sent for several days. The date line should reflect the date the letter is actually sent, not the date it was written. If you draft on October 10 and send on October 15, write October 15.
Block format date line in context
The date line doesn't stand alone. It's one element in a sequence: sender's address, date, inside address, reference line (if used), salutation. Each part feeds the next, and each one follows spacing conventions that the block format defines precisely.
The inside address that follows the date line has its own rules for name, title, company, and street. Those are covered in full in how to write a business letter inside address. Getting the date right and then placing it above a badly formatted inside address still produces a document that reads as unprofessional.
Block format became the standard partly because it's easy to apply consistently. Every element starts at the left margin. The date line benefits from that consistency as much as any other part of the letter. Apply the rules once and they hold across every letter you write.