And now for something comepletely different . . .

I am a native Dutch speaker and as a former student of the English language I was asked by a friend of mine to translate the (Dutch) website of his small company into English. This is a company which develops software for electronic bookkeeping. I made clear to him that I don't know much about bookkeeping, but I would be glad to do him a favour and give it a shot. Most of it, I think, turned out pretty well but some vocabulary items seem to be very strong jargon and it's hard, sometimes even impossible to find their English equivalents in (online) Dictionaries.

On this forum I am hoping to find someone to help me out with the terminology I struggle most with. In some cases more than one option might even be possible, but I'm just wondering what the most customary way is of saying it. I do realise you might not know the Dutch terms, but hopefully the word I'm looking for can be understood from it's options or context. I'm doubtful about the options in brackets, but just added them to show you the options I've come accross.

Thank you so much beforehand!

Aanmaning --> reminder / final request / final notice / exhortation  

Aanvullen --> (complete) / (replenish) / supplement

Afhandelen --> (handle) / settle

Bankmutatie --> (bank import) / bank movement / (general ledger)

Budgethouder --> budget holder / authorizing officer

Clientgelden --> cliënt money

Dagboek --> (journal) / (diary) / daybook

Declaratie --> expenses / expenses account

Declareren --> declaring expenses / (claiming expenses)

Einddatum --> end date / maturity date

Factureren --> invoicing / (billing --> AE?)

Factuurtermijn --> invoicing term / invoicing period / (billing term / period --> AE?)

Inkomsten --> incomes / revenues (dependent on context I think)

Inkoopafdeling --> buying department / purchasing department / procurement department

Inkoopfactuur --> buying invoice / purchasing invoice / procurement invoice

Inkoopkosten --> buying costs/ purchasing costs/ procurement costs

Inkooporder --> buying order/ purchasing order / procurement order

Mutatieoverzicht --> overview of movements / (statement of changes) / (statement of equity)

Onkostendeclaratie --> expense claim / cost claim / expense report

Onkostenrekening --> expense account

Opzeggen (van contract) --> terminate a contract / break a contract

Tegenboeking --> (counter issue) / contra entry

Verlengen (van een contract) --> renew a contract / renew a lease / (extend the term of a contract) / (extend the term of a lease)

Verplichtingen --> obligations / liabilities

Verplichtingenadministratie --> liability administration