People Cost Forecasting
How to build a forward-looking people cost model — factoring in planned hires, pay rises, NI changes, and pension increases — to protect cash flow.
Why People Costs Are Hard to Forecast
People costs are deceptively difficult to forecast accurately because they change in multiple ways simultaneously:
- Planned hires add new fixed costs at different points in the year
- Pay reviews create uplift on existing costs (usually annual)
- Employer NI thresholds and rates change each April
- Pension auto-enrolment contributions are percentage-based and scale with wages
- Attrition removes costs (often unplanned) while rehiring adds costs back
A payroll model that is only updated when something changes will be systematically out of date. Build a rolling 12-month forecast and refresh it monthly.
Building a People Cost Forecast in AskBiz
Start with your current payroll data and model forward:
1. Ask AskBiz: *'What is my current monthly payroll cost broken down by employee and role?'*
2. Add planned hires — enter each planned hire with start date and salary
3. Apply a pay rise assumption — e.g. 4% across all staff in April
4. Add employer NI — AskBiz can model NI at current rates against each salary
5. Add pension contributions at your current rate
6. Model planned leavers if you know of any
The result is a month-by-month payroll cost forecast for the next 12 months, which feeds into your cash flow forecast.
Scenario Planning for People Costs
Build three scenarios:
Conservative (base): only confirmed hires, current pay rise assumption, no unexpected turnover.
Growth (upside): confirmed + planned hires, higher pay rise to remain competitive, normal turnover.
Constrained (downside): only backfill hires, pay freeze or below-inflation rise, higher turnover than expected.
Ask AskBiz: *'What is the difference in total payroll spend over the next 12 months between my conservative and growth hiring scenarios?'* — this quantifies what the hiring plan actually costs before you commit.
Employer NI and Government Levy Changes
UK employer National Insurance is a variable cost that changes with government policy. From April 2025, employer NI rates increased to 15% and the secondary threshold dropped — increasing the NI cost for many small employers.
When building your payroll forecast:
- Always use the current rate from HMRC (check gov.uk annually)
- Model the impact of NI changes on your total payroll cost — for a team of 20 at average salary, a 1% NI rate change can add £5,000–15,000 to annual costs
- Factor in the Employment Allowance if you qualify (reduces employer NI by up to £10,500/year for eligible businesses)
Ask AskBiz: *'What is my estimated employer NI cost for this year based on current headcount and salaries?'*