Time and Materials (T&M)

Time and materials (T&M) is a billing model where a client pays for actual hours worked at agreed rates plus any direct expenses incurred, with no capped total; the client bears the scope and duration risk.

How T&M billing works

The firm and client agree on four elements before work begins:

1. Role rates from the firm’s rate card, stated as hourly or daily figures
2. Reimbursable expense categories and any applicable markup
3. Reporting cadence, such as weekly timesheets submitted against monthly invoices
4. An optional not-to-exceed (NTE) cap

The client is invoiced for hours consumed multiplied by the agreed rate, plus approved expenses. If an NTE cap exists, billing stops at the cap even if work continues, which shifts overrun risk back to the firm.

When T&M is appropriate

T&M suits work where scope is genuinely uncertain at the time of contracting. Common cases include discovery and assessment engagements, software implementations with evolving requirements, ongoing advisory retainers billed monthly, and work where the client requires direct visibility into effort consumed.

It is less appropriate when the client has a fixed budget and no appetite for overrun, or when the firm has sufficient historical data to price the work as fixed-fee at a healthy margin. In those situations, T&M delays the pricing decision rather than resolving it.

Margin protection on T&M

Because there is no budget ceiling, margin on T&M comes from three operational controls rather than from a contract ceiling.

Rate discipline means quotes are built from the approved rate card and blended rate structures, not negotiated ad hoc per deal. Discounting without approval erodes margin directly.

Timesheet accuracy means hours are logged against the correct engagement and role within the billing period. Hours that go unrecorded cannot be invoiced, and misallocated hours distort realization rate data.

Expense governance means only pre-approved expense categories are passed through to the client, and markup is applied consistently rather than case by case.

Common pitfalls

Scope expansion on T&M engagements is easy to miss because there is no budget ceiling to breach. Without regular burn reporting, clients can be surprised by cost at invoice time, which creates disputes and damages the relationship.

Rate inconsistency across team members, whether from ad hoc discounts or undocumented role changes, makes the engagement’s effective blended rate drift below what the margin model assumed.

An NTE cap, once agreed, is often treated by clients as a target rather than a ceiling, leading to scope being packed up to the limit regardless of whether the work requires it.