Expenses: the forgotten line items
Consultants often bill expenses alongside fees: travel, materials, subcontractor costs. These line items are easy to under-bill when you are assembling an invoice from memory at the end of a long engagement. And once an expense is left off, recovering it means an awkward correction invoice, which most consultants simply never send.
The discipline that fixes this is the same one that fixes follow-ups: a system that does not rely on memory. When your invoicing routine captures expenses as they happen and your reminders chase the complete invoice automatically, the small amounts stop leaking. Over a year of engagements, those recovered line items add up to real money.
The same applies to scope changes. Consulting engagements evolve, and extra work agreed over a call is easy to forget by invoicing day. A habit of logging billable extras as they occur, paired with reminders that chase the full amount, means the invoice reflects the work you actually did.
Put together, these habits form a simple operating principle: nothing about your money should depend on memory. Capture it when it happens, invoice it completely, and let the follow-up run itself. That is the whole job InvoiceTact was built to do.