Questions people ask
Can I write my own prenup without a lawyer?
The short answer
A prenuptial agreement written without counsel may be challenged on grounds that include disclosure and independent representation, which is why attorneys are usually involved on both sides. Whether a specific agreement holds is a legal question for a family-law attorney.
The longer answer
We store documents. We do not draft them, review them or advise on them, and we would rather say so plainly than let a conversation about storage drift into legal advice. That line holds even for a question as simple as this one.
The two grounds named in the answer point at practical things. Disclosure concerns whether each person knew what the other had. Independent representation concerns whether each person had their own advice. An agreement written at a kitchen table can have neither, and nothing about where it is kept changes that.
Template agreements are easy to find, and they tend to look complete. What a template cannot supply is the part that makes an agreement particular to two people: accurate schedules, a clear record of what each person was shown, and an attorney on each side who can later say what their client understood. Two people who agree on everything, and trust each other completely, are the ones most tempted to skip those steps. A template cannot tell you what it left out.
The rules are set state by state. If you are asking this question, ask a family-law attorney where you live, and ask before the wedding date is close enough to become part of the argument. Asking early also leaves time for the disclosure the agreement depends on. Some couples use one attorney to draft and a second to review for the other side; whether that is enough is also a question for counsel.
Keep the paper trail from the signing
Whoever writes the agreement, the questions it may later face tend to be about what each person knew and when. The answers sit in papers people rarely think to keep: the financial statements each side exchanged, the dated email or letter that sent the draft, each attorney's engagement letter. Some of it exists only in an inbox, which is its own kind of fragile. Ask your attorney which of these to hold on to, and for how long.
Those papers are part of the record as much as the agreement is. Kept together and dated, they show the circumstances of the signing long after anyone remembers them clearly. The original agreement and every attachment to it belong in the same place. If a schedule was exchanged by email, keep the message as well as a printout, because the message carries the date.
A vault does not make an agreement fair. It keeps the evidence of how the agreement was made. That is all it can do. If the agreement itself is the problem, the fix is an attorney, not a better box.