Bookkeeping for the interim manager: agencies, false self-employment and expenses

One client, a long assignment: the DBA question

Interim assignments rarely last a week. Six months extended to twelve, on fixed days, with a laptop from the client and a seat in the management team: from a distance that resembles employment. Since 2025 the tax authorities actively enforce the rules on false self-employment, and in well-paid interim roles they look at the actual situation, not at what the contract says. See false self-employment and the DBA act.

What helps: your own assignment description with a result rather than a job title, your own rate and terms, working with your own tools where possible, your own liability insurance, and several clients across the year. A model agreement is never enough by itself: it only protects if practice matches it, see model agreements and how many clients you need.

Invoicing through an agency

Many interim assignments run through an intermediary or broker. You then invoice the agency, not the end client, with 21 per cent VAT. Watch three things in their terms: the payment period, whether you invoice yourself or they issue a self-billing invoice, and whether there is a non-compete clause barring you from working directly with the client afterwards.

If the agency issues the invoice for you, check it anyway: your VAT number, your Chamber of Commerce number, the right number of hours and the right VAT amount. You remain responsible for what ends up in your return. And keep your own hours log, even if the agency uses a portal; see keeping an hours log.

Passing on travel and other costs

If you drive to the client in your private car, you deduct € 0.25 per kilometre from your profit. If you pass those kilometres on to your client, that is simply revenue and you charge 21 per cent VAT on it, even though you paid no VAT on those kilometres yourself. The same applies to train tickets and hotel stays you pass on: the rate of your service sets the rate on the invoice. See passing costs on to your client and travel costs.

Your cost side is otherwise straightforward: laptop and phone for the business share, trade literature and training, your professional liability insurance, network memberships and your website costs. A home office is rarely deductible, but your desk, chair and screen are; see a home workspace and phone, laptop and internet for business.

Between two assignments

Interim work comes in waves: eight months full, then two months of nothing. Those quiet months are no tax problem, but they are a cash flow question: your VAT for the previous quarter still has to be paid and your income tax assessment comes later. So set aside a fixed percentage per invoice, see how much to set aside and building a buffer.

Hours without an assignment are not lost for the hours criterion: acquisition, networking, admin and training count towards the 1,225 hours you need for the self-employed deduction. Do record them. If your rate rises sharply and you work structurally at this level, at some point the question of whether a private limited company pays off becomes interesting; see sole proprietorship or private limited company.

Frequently asked questions