Glossary
Billing Glossary —
Billing Glossary —
Every term, explained simply.
No MBA required. Just plain-language definitions for every billing, invoicing, and time tracking term you'll encounter. Bookmark it. You'll be back.
A
Accounts Aging
How long your invoices have been unpaid. 30 days is normal. 90 days is a problem. If you're not tracking this, you're not tracking your cash flow.
B
Billable Hours
Hours you can charge a client for. The ones that pay your rent. Everything else is overhead.
Burn Rate
How fast you're spending money. Track it or regret it. Calculated monthly: total expenses divided by one. Simple math, existential implications.
C
CLI
Command-line interface. Track time without a browser. Developers love it. Everyone else thinks we're weird for preferring it.
Client Portal
A page where clients see their invoices. No login, no password reset emails. One link, all their billing history. Self-service that actually serves.
E
Expense Report
A list of what you spent. Attach receipts. Get reimbursed. If you're doing this in a spreadsheet, you're doing it wrong.
F
Fixed-Price Project
Client pays a flat fee. You eat the risk if it takes longer. Track hours anyway — you need to know if you're making or losing money.
Freelancer
Someone who trades time for money without a W-2. Most of our users. The backbone of the modern economy, perpetually undercharging.
H
Hourly Rate
What you charge per hour. Multiply by tracked hours to get the invoice amount. If you haven't raised yours in two years, it's too low.
I
Invoice
A document saying "you owe me this much." Send it. Get paid. The faster you send it after doing the work, the faster you get paid.
M
MIT License
The most permissive open source license. Do whatever you want with the code. Fork it, modify it, sell it. Miru uses it because we believe billing software shouldn't lock you in.
N
Net 30
Payment due 30 days after invoice. Industry standard. Often ignored. Put a Stripe payment link on the invoice and most clients pay in under a week.
Non-Billable Hours
Hours you work but can't charge for. Internal meetings, admin, learning. If this exceeds 30% of your week, something is wrong.
O
Open Source
Software with publicly available source code. No vendor lock-in. If we disappear tomorrow, you still have the code. That's the point.
P
Per-Seat Pricing
Charging per user per month. Punishes growth. A 50-person team on Harvest pays $540/month. On Miru, that's $50. We charge $1/member instead because it's honest.
Project Profitability
Revenue minus cost for a project. The number that tells you if the work was worth doing. Most agencies don't calculate this until it's too late.
R
Retainer
A recurring monthly agreement. Client pays X/month for Y hours of your time. Predictable revenue for you, guaranteed availability for them.
S
Self-Hosting
Running the software on your own servers. You own the data. No third-party subprocessors. No "we updated our privacy policy" emails. Your hardware, your rules.
Stripe
Payment processor. Miru uses it so clients can pay invoices with one click. Cuts average payment time from 30 days to under a week.
T
Time Entry
A record of hours worked. Project, duration, date, note. That's it. If your time tracking tool asks for more than that, it's asking too much.
Time Tracking
Recording how long you spend on work. The foundation of hourly billing. Do it at the end of each task, not at the end of the day, or the data is fiction.
U
Utilization Rate
Billable hours divided by total hours. Target: 70-80%. Below 60% is a problem. Above 90% means your team is burning out. The single most important metric for service businesses.
Know the terms. Now use the tool.
Miru handles time tracking, invoicing, expenses, and payments. Free for teams of five. $1/member after that. Or self-host for $0 forever.