Before the Series A, Read the Side Letters

A lot of founders treat side letters like closing debris.

The financing closes, the money hits the account, the main documents go into the folder, and the side letters sit somewhere nearby looking harmless. Maybe one investor wanted information rights. Maybe another wanted pro rata rights. Maybe someone got a special notice right, a Major Investor status point, a small consent right, or a promise that the company would do something later.

None of it feels like a problem at the time.

Then the Series A starts.

That is when the side letters come back into the room.

A side letter is not a side issue

The main financing documents tell part of the story. Side letters can tell the rest.

A side letter may not amend the charter or show up clearly on the cap table, but it can still affect how the company operates and how the next financing gets done. It can create rights that matter when new investors are reviewing the company, when existing investors want allocations, or when counsel is trying to understand who is entitled to what.

The issue is not that side letters are bad. They are often useful. They can help close a round, address a specific investor concern, or avoid overcomplicating the main financing documents.

The issue is that companies often stop tracking them once the round is closed.

That is the mistake.

The rights that tend to matter later

Before a priced round, founders should know whether any prior side letters include rights around:

• Pro rata participation
• Information delivery
• Major Investor status
• Notice of future financings
• Board observer rights
• Consent or consultation rights
• MFN provisions
• Transfer rights
• Confidentiality carveouts
• Investor-specific reporting
• Obligations to update documents later

Some of these rights are manageable. Some are duplicative. Some are stale. Some are vague enough to become annoying right when the company is trying to move quickly.

The practical problem is not always that the right exists. The practical problem is that nobody can quickly answer what exists, who has it, and whether it still applies.

Why this matters before the Series A

A Series A investor is not just looking at the cap table. They are looking at the company's legal architecture.

If the company has several prior side letters, those side letters may affect allocation discussions, closing deliverables, investor communications, and the drafting of the new financing documents. They may also affect how clean the company looks during diligence.

A messy side letter record can create awkward questions:

• Who has pro rata rights?
• Do any investors have rights that conflict with the new financing structure?
• Did anyone get information rights that the company has not been honoring?
• Are there MFN provisions that were triggered and never addressed?
• Did an early investor get something that now needs to be disclosed, waived, or folded into the new documents?

None of these questions is necessarily fatal. But they can slow the process, weaken leverage, or create unnecessary cleanup work at exactly the wrong time.

The cap table will not save you

A cap table is important, but it does not show every legal right.

The spreadsheet may show who owns what. It usually does not show who has side letter rights, who received special promises, who can participate in future rounds, or who must receive particular information.

The spreadsheet should follow the documents, not replace them.

If the only source of truth is the cap table, the company may miss rights that matter during diligence. If the only source of truth is a folder of unsigned PDFs, the company has a different problem.

The goal is simple: know what was signed, know what it means, and know what needs to be cleaned up before the next financing starts.

The founder version of diligence

Founders do not need to turn every side letter review into a giant legal project. But before a priced round, someone should build a clean summary of the side letter landscape.

That summary should answer:

• Which investors have side letters?
• What rights does each side letter provide?
• Are any rights tied to ownership thresholds?
• Are any rights triggered by a future financing?
• Are any rights duplicative, inconsistent, or unclear?
• Has the company been complying with any ongoing obligations?
• Should any rights be waived, terminated, amended, or carried forward?

This does not need to be dramatic. It just needs to be done before the company is under pressure.

Timing matters

The worst time to discover an old investor right is after the lead investor has already circulated financing documents.

At that point, the company may be trying to manage allocations, answer diligence questions, coordinate signatures, and keep the round on track. A forgotten side letter can suddenly become everyone's problem.

The better move is to review the side letters before the process gets hot.

That gives the company time to decide whether a right is still relevant, whether it needs to be disclosed, whether it needs a waiver, and whether it should be reflected in the new financing documents.

The practical takeaway

Side letters can be useful tools. They can also become a second layer of governance if no one tracks them.

Before the Series A, founders should read the side letters, summarize the rights, and clean up anything that could confuse the next round.

A side letter is not a side issue. It is part of the company's legal record. Treat it that way.