How do I forecast quarterly tax payments in a rolling cash flow forecast?

[NoraA]

I’m trying to build a rolling 12-month cash flow forecast for my small service business, but I keep getting stuck on how to realistically project my quarterly tax payments. My revenue is fairly predictable, but my expenses are lumpy, and I’m never sure if I’m setting aside too much or too little when I look at the upcoming months.

[ScarlettFA]

I keep a separate tax bucket and look at the last two years of quarterly payments to sanity check what to set aside. Revenue is steady enough that I can eyeball the profit month to month, but when a big software bill lands in quarter two the tax piece feels like a surprise. I have noticed that when I keep a consistent percentage of monthly net it helps the forecast feel less shaky even if the tax numbers do not line up exactly every quarter.

[Sophia85]

It still scares me sometimes because the lumpier expenses throw the cash balance off and I end up under reserving. Some months I have a big repair some months nothing and I worry I am either sitting on too much cash or sitting with a tax bill I cannot cover if profits shift.

[LilyW]

Do you think the real issue is the quarterly rhythm or is it just the swings in expenses I keep wondering whether adjusting timing of some spends would make the tax piece easier to forecast?

[NoraS]

One thing that helped me briefly was chasing the idea of a rolling forecast and at the same time drifting into pricing cadence and when I invoice it felt like chasing separate problems but I kept coming back to the tax bucket and balance not sure if that is the right track but it is what I tried.