[zomgwat]

After spending years maintaining a home grown billing system, I recommend against rolling your own. It's frustrating to spend time adding yet another hack to account for some new use case while there is a stack of other priorities waiting (that more directly impact the value of the business). I learned through experience that billing systems are complex and the complexity can sneak up on you over time.

[mgkimsal]

> It's frustrating to spend time adding yet another hack to account for some new use case while there is a stack of other priorities waiting

The key diff between 'build' vs 'buy' seems to come down to an accommodation of one-off and sometimes frankly 'wrong' processes.

Using off the shelf prevents accommodating many oddities companies have accumulated (via growth, acquisition, whatever).

Build from scratch seems to always implicitly include "we'll handle every weird-ass edge case anyone might come at us with in the future, because we built it ourself".

There could be a middle ground of "build with certain parameters, but also normalize some existing processes by refusing to spend hundreds of hours building weird accounting processes for 1 customer someone because a salesperson needed to hit their target and told them anything was possible".

Dealt with accounting stuff years ago, and ... there weren't any accounting systems which could simply/easily handle 20 years of homegrown cruft. "If the customer number starts with P or X, and the account rep is Randy, they get a 5% discount until next summer". They had... 5000 customers, and about 30% of them had ad-hoc 'rules' like that. Hundreds of business rules various people just 'knew'. Just documenting and classifying them can take weeks.

I'm not saying no commercial systems can ever support that level of customization, but "we'll import all your stuff with 3 mouse clicks"-style marketing fluff ignores the reality that ... you have to adapt your business some, or you have to build in house. But even building in house, you still need to adapt your business processes to reduce/eliminate ad-hoc rules that people just yell down the hall to the accounting team.

[zomgwat]

It sounds like we've had very similar experiences. The fact that what you've described is so similar to what I've seen may say something. There are reasons to have a bespoke billing system but people should try REALLY hard to avoid the situation.

Something I saw regularly with one-off style sales deals was not accounting for the collateral damage to business processes like end-of-month accounting. It's not just the development costs for adding support to things like subscriptions. Changes ripple all the way through the business. Updates to the bespoke billing system (and related business processes) end up half-baked because they aren't a core part of the business. I've seen sales deals end up as a net loss over time due to the increased labor costs on the backend. Having some reasonable constraints that an off-the-shelf product will intrinsically enforce can prevent a lot of pain for all involved.

[mgkimsal]

It's never pain that the sales folks have to bear, it seems. :)

[zomgwat]

Ha. Nope.