The money is committed. The cash is not. Waterline models the distance between those two things — period of performance, drawdown schedule, reimbursement lag, and the match you owe against every dollar you bill.
It accrues as a percentage of what you have billed, and it has to be satisfied inside each budget period. A funder does not let you under-match in year one and make it up in year three.
So Waterline schedules it on the rhythm you bill on, and weights it by what you actually billed rather than by the calendar. A month you billed nothing is a month you owe nothing.
| How you bill | When the match is due |
|---|---|
| Monthly, as incurred | each month, weighted by what you billed |
| In arrears | at the close of each budget period |
| Advance | at the close — being paid early does not move the proof |
| Against milestones | per milestone, in proportion to the draw |
Cost share owed · two budget periods
The obligation rises with billing. The dashed rules are the two moments a funder checks it.
One field on a budget period. The same budget spreads over a longer window, reimbursement in arrears arrives later, and the cost-share deadline moves with the period end. Every figure downstream follows.
The weeks between sending an invoice and the money landing are where a fully funded organization runs out of cash. Set the lag once per award and it applies to every draw.
Negotiated rates, direct and indirect split per category, and an SF-424A that imports and exports rather than being retyped.
A $2.4m award at 20% cost share, billed monthly, is not one $480,000 obligation at the end. It is a rising line you owe against as you draw — and if your runway ends before the second period closes, the match you have not yet made is money you have promised and do not have.
That is the number Waterline shows you, and it is the reason the software exists.