Agradezco haber escrito el informe antes de la reunión.

Agradezco is the 1st person singular present of agradecer: I am grateful / I appreciate / I’m thankful.

So:

• agradezco = I appreciate / I’m grateful for
• agradecer is the verb form meaning to appreciate, to be thankful for

In this sentence, the speaker is saying they appreciate a completed action: having written the report before the meeting.

Also note that agradecer has a spelling change in the yo form:

• agradecer → agradezco
• similar to conocer → conozco

The z appears to keep the correct sound before -co.

Haber escrito is the perfect infinitive. It means to have written / having written.

It is used here because the writing happened before the feeling of appreciation.

• Agradezco escribir... would suggest appreciating the act of writing in a more general or ongoing sense.
• Agradezco haber escrito... specifically refers to a completed action.

So the sentence highlights that the report was already written, and now the speaker is grateful for that fact.

It is made of:

• haber = the auxiliary verb to have in the infinitive
• escrito = the past participle of escribir

Together they form the perfect infinitive:

• haber escrito = to have written

This structure is common after verbs and expressions like:

• lamentar haber dicho eso = to regret having said that
• alegrarse de haber venido = to be glad to have come
• agradecer haber terminado = to appreciate having finished

Because escribir has an irregular past participle:

• escribir → escrito

Some common irregular past participles are:

• abrir → abierto
• decir → dicho
• hacer → hecho
• poner → puesto
• romper → roto
• ver → visto
• volver → vuelto

So haber escrito is the correct form.

Normally, the natural interpretation is that the speaker wrote it.

That is because in Spanish, when you use a structure like:

• Agradezco haber escrito...

the subject of haber escrito is usually understood to be the same as the subject of agradezco, which is I.

So this means:

• I appreciate having written the report before the meeting.

If you wanted to say that someone else wrote it, Spanish would usually use a different structure, for example:

• Agradezco que hayas escrito el informe antes de la reunión. = I appreciate that you wrote the report before the meeting.

Because after agradecer, if you introduce a new clause with que, Spanish normally uses the subjunctive, not the indicative.

So you would say:

• Agradezco que hayas escrito el informe...

not:

• Agradezco que he escrito...

But when the subject is the same as the main verb, Spanish often prefers the infinitive structure:

• Agradezco haber escrito...

That is more compact and very natural.

The main difference is who did the action.

Agradezco haber escrito...

• Usually the speaker did the writing.
• I appreciate having written...

Agradezco que hayas escrito...

• Usually you did the writing.
• I appreciate that you wrote...

So the infinitive version usually keeps the same subject, while the que + subjunctive version is used when the subject changes.

Antes de means before.

When antes is followed by a noun, Spanish uses de:

• antes de la reunión = before the meeting
• antes de clase = before class
• antes de la cena = before dinner

It also uses de before an infinitive:

• antes de salir = before leaving
• antes de escribir = before writing

But if a full clause follows, Spanish usually uses antes de que + subjunctive:

• antes de que empiece la reunión = before the meeting starts

Spanish uses definite articles more often than English.

Here:

• el informe = the report
• la reunión = the meeting

These articles suggest the speaker has a specific report and a specific meeting in mind, probably already known from context.

English sometimes drops articles where Spanish keeps them, but in this sentence the articles are fully natural in both languages.

Yes. Redactar is often used for writing/drafting a document, and it can sound a bit more formal or more specifically related to producing a text.

So:

• escribir el informe = to write the report
• redactar el informe = to draft/write up the report

Both are correct, but redactar is especially common with things like:

• informes
• cartas formales
• documentos
• informes técnicos

Yes, but it sounds a bit formal, reflective, or written.

A Spanish speaker would understand it perfectly, but in casual conversation people might more often say things like:

• Me alegro de haber escrito el informe antes de la reunión.
• Estoy contento de haber escrito el informe antes de la reunión.
• Menos mal que escribí el informe antes de la reunión.

So Agradezco haber escrito... is correct and natural, but it has a slightly more thoughtful or formal tone.

Not always. Agradecer can mean either:

1. to thank
2. to appreciate / be grateful for

Examples:

• Te agradezco tu ayuda. = Thank you for your help / I appreciate your help.
• Agradezco haber venido. = I’m grateful to have come / I appreciate having come.

In your sentence, it is not really thanking a person directly. It is more like expressing appreciation for a completed action.

Yes, a little.

The original order is the most neutral:

• Agradezco haber escrito el informe antes de la reunión.

You could move parts for emphasis, for example:

• Antes de la reunión, agradezco haber escrito el informe.

That is grammatically possible, but it sounds more marked and less neutral. In most cases, the original version is best.

Yes. Both are valid depending on how you phrase the English sentence.

• Agradezco haber escrito el informe...
  • I appreciate having written the report...
  • I’m grateful to have written the report...

Spanish haber + past participle does not force one single English translation. The best translation depends on the wording that sounds most natural in English.

Because Spanish often leaves out subject pronouns when the verb already makes the subject clear.

• Agradezco already tells you the subject is I
• so yo is unnecessary

You could say:

• Yo agradezco haber escrito el informe...

but that would add emphasis, contrast, or special focus. Normally, just Agradezco... is enough.